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UNIVERSITY OF CALIFORNIA
COLLEGE OF AGRICULTURE
AGRICULTURAL EXPERIMENT STATION
BERKELEY, CALIFORNIA
THE RED OR ORANGE SCALE
Br H. J. QUAYLE
BULLETIN No. 222
(Berkeley, Cal., July, 1911)
WV. W. SHANNON -
SACRAMENTO
- -SUPERINTENDENT OF STATE PRINTING
1911
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BENJAMIN IDE WHEELER, President of the University.
EXPERIMENT STATION STAFF.
E. J. WICKSON, M.A., Director and Horticulturist.
E. W. HILGARD, Ph.D., LL.D., Chemist (Emeritus).
W. A. SETCHELL, Ph.D., Botanist.
LEROY ANDERSON, Ph.D., Dairy Industry and Superintendent University Farm Schools.
M. E. JAFFA, M.S., Nutrition Expert.
R. H. LOUGHRIDGE, Ph.D., Soil Chemist and Physicist (Emeritus).
C. W. WOODWORTH, M.S., Entomologist.
RALPH E. SMITH, B.S., Plant Pathologist and Superintendent of Southern California
Pathological Laboratory and Experiment Station.
G. W. SHAW, M.A., Ph.D., Experimental Agronomist and Agricultural Technologist, in
charge of Cereal Stations.
E. W. MAJOR, B.Agr., Animal Industry.
B. A. ETCHEVERRY, B.S., Irrigation Expert.
F. T. BIOLETTI, B.S., Viticulturist.
W. T. CLARKE, B.S., Assistant Horticulturist and Superintendent of University Exten-
sion in Agriculture.
JOHN S. BURD, B.S., Chemist, in charge of Fertilizer Control.
J. E. ColT, Ph.D., Assistant Pomologist, Plant Disease Laboratory, Whittier.
GEORGE E. COLBY, M.S., Chemist (Fruits, Waters, and Insecticides), in charge of
Chemical Laboratory.
H. J. QUAYLE, M.S., Assistant Entomologist, Plant Disease Laboratory, Whittier.
H. M. HALL, Ph.D., Assistant Botanist.
C. M. HARING, D.V.M., Assistant Veterinarian and Bacteriologist.
E. B. BABCOCK, B.S., Assistant Agricultural Education.
W. B. HERMS, M.A., Assistant Entomologist.
J. H. NORTON, M.S., Assistant Chemist, in charge of Citrus Experiment Station, River-
side.
W. T. HORNE, B.S., Assistant Plant Pathologist.
C. B. LIPMAN, Ph.D., Soil Chemist and Bacteriologist.
R. E. MANSELL, Assistant Horticulturist, in charge of Central Station grounds.
A. J. GAUMNITZ, Assistant Agronomist, University Farm, Davis.
N. D. INGHAM, B.S., Assistant in Sylviculture, Santa Monica.
T. F. HUNT, B.S., Assistant Plant Pathologist.
P. L. McCREARY, B.S., Chemist in Fertilizer Control.
E. H. HAGEMANN, Assistant in Dairying, Davis.
R. M. ROBERTS, Farm Manager, University Farm, Davis.
B. S. BROWN, B.S.A., Assistant Horticulturist, University Farm, Davis.
J. I. THOMPSON. B.S., Assistant Animal Industry, Davis.
HOWARD PHILLIPS, B.S., Assistant Animal Industry, Davis.
J. C. BRIDWELL, B.S., Assistant Entomologist.
C. H. MCCHARLES, M.S., Assistant Agricultural Chemical Laboratory.
E. H. SMITH, M.S., Assistant Plant Pathologist.
C. 0. SMITH, M.S., Assistant Plant Pathologist, Plant Disease Laboratory, Whittier.
F. E. JOHNSON, B.L., M.S., Assistant Soil Chemist.
B. A. MADSON, B.S.A., Assistant Experimental Agronomist.
WALTER E. PACKARD, M.S., Field Assistant Imperial Valley Investigation, El Centro.
P. L. HIBBARD, B.S., Assistant Fertilizer Control Laboratory.
L. M. DAVIS, B.S., Assistant in Dairy Husbandry, University Farm, Davis.
S. S. ROGERS, B.S., Assistant Plant Pathologist, Plant Disease Laboratory, Whittier.
L. BONNET, Assistant Viticulturist.
H. A. RUEHE, B.S.A., Assistant in Dairy Husbandry, University Farm, Davis.
F. C. H. FLOSSFEDER, Assistant in Viticulture, University Farm, Davis.
S. D. WILKINS, Assistant in Poultry Husbandry, University Farm, Davis.
C. L. ROADHOUSE, D.V.M., Assistant in Veterinary Science.
F. M. HAYES, D.V.M., Assistant Veterinarian.
F. L. YEAW, B.S., Assistant Plant Pathologist, University Farm, Davis.
M. E. STOVER, B.S., Assistant in Agricultural Chemical Laboratory.
W. H. VOLCK, Field Assistant in Entomology, Watsonville.
E. L. MORRIS, Field Assistant in Entomology, San Jose.
E. E. THOMAS, B.S., Assistant Chemist, Plant Disease Laboratory, Whittier.
A. B. SHAW, B.S., Assistant in Entomology.
G. P. GRAY, M.S., Chemist in Insecticides.
H. D. YOUNG, B.S., Assistant in Agricultural Chemistry, Plant Disease Laboratory.
Whittier.
A. R. TYLOR, B.S., Assistant in Plant Pathology, Plant Disease Laboratory, Whittier.
E. W. RUST, A.B., Assistant in Entomology, Plant Disease Laboratory, Whittier.
L. T. SHARP, B.S., Assistant in Soils.
W. W. CRUESS, B.S., Assistant in Zymology.
J. F. MITCHELL, D.V.M., Assistant in Veterinary Laboratory.
J. C. ROPER, Patron, University Forestry Station, Chico.
E. C. MILLER, Foreman, Forestry Station, Chico.
D. I, BUNNELL, Secretary to Director.
CONTENTS.
HISTORICAL ___-----_--__
DISTRIBUTION --------- ---..--___
ECONOMIC IMPORTANCE -__
FOOD PLANTS -_--____-_-_-- -- --_.__-
DESCRIPTION OF THE STAGES ------___________-.
FIRST LARVAE STAGE __________
SECOND STAGE FEMALE -
THE ADULT FEMALE ______
THE SECOND STAGE MALE_
THE MALE PROPUPA
TIE MIALE PUPA _______
TIE ADULT MIALE _________________
LIFE HISTORY AND HABITS --_________
THE ACTIVE LARVA ___ ___ --
SETTLING OF TIE LARVAE _____________
FORMATION OF THE SCALE COVERING --___-_____-___.
TIE FIXED YOUNG
Molting --_ --- --
THE ADULT MALE __________
THE ADULT FEMALE _______________
LENGTH OF ADULT LIFE______
AGE AT WIIICI YOUNG ARE PRODUCED -.-
A SPIDIOTUS AURANTII--DEVELOPMENT -T
EMBRYONIC DEVELOPMENT
PARTHENOGENESIS
EMERGENCE OF YOUNG -
DO THE INSECTS MovE AFTER BECOMING FIXED -_-
SEASONAL IIISTORY -
ANNUAL PROGENY _
MORTALITY --
LOCOMOTION AND SPREAD _____
RATE OF TRAVEL OVER SMOOTII SURFACE________
RATE OF TRAVEL OVER SAND AND ORCHARD SOIL__ .-
TIE WIND _________
PARASITES -_------
APHELINUS DIASPIDIS HOw. _________
Economic Value __
Description of the Stages_____-_ _______
Life History and Habits --___________--_--
KEY TO TIE SPECIES RECORDED FROM C. AURANTII____
PROSPALTELLA AURANTII How. __--
COCCOPITAGUS LUNULATUS HoW. __-__
ASPIDIOTIPIIAGUS CITRINUS Craw. -- -------
SIGNIPHORA OCCIDENTALIS Hlow. -- --------
APHYCUS IMMCACULATUS IHow. _____-------
ALAPTUS ERIOCOCCI Girault _
PAGE.
__ 99
- _----- 101
_--_____ 101
102
__ 105
-_ _10(
-------- 10G
______ 10
107
_---__-_ 107
___ 307
1_ 08
10S
10S
10!
]09
-- 110
]ll
114
- - 1 1-
117
l1S
Irs
119
120
121
121
121
12,-)
12(;
127
12!
.. 130
131
132
132
.-- 133
--*- ---- 132;
S13G
--------- 137i
13S
138.
13S,
IV CONTENTS.
PAGE.
PREDATORY ENEMIES _____---------------- -138
RIIIZOBIUS LOPHANTHIzE Blaisd. ------------..-----------138-
The Eggs ------- --------------- 39
The Mature Larva 13-_________9___
The Adult -------------------40
ORCUS CIIALYBEUS Boisd. _______ _____ .141
OTIER ENEMIES __--------- ------ 141
THE YELLOW SCALE (CRYSOMPIALUS AURANTII var. CITRINUS Coq.)---- 141
EcoNoMIC IMPORTANCE -----__-__ ------_ _ 142
DIFFERENCE BETWEEN TIE RED AND YELLOW SCALES-- 1-44
PARASITES _-- ---- 145
Aspidiotiphagus citrinus Craw. ___-- __145
The Egg --- -------------------------- 14
The Mature Larva ___.. ___________- 146
The Pupa ---- ---_ __- 146
The Adult --- -- -- --__--- 146
SYSTEMATIC POSITION OF CHRYSOMPIALUS AURANTII MASK.. 148
BIBLIOGRAPHY 149
THE RED OR ORANGE SCALE.
Chrysomphalus aurantii Mask.
By H. J. QUAYLE.
HISTORICAL.
Chrysomphalus aurantii was first described from New Zealand by
W. M. Maskell in 1878. The specimens described were found infesting
oranges and lemons imported into New Zealand from Sydney. Two
years later Professor Comstock observed a scale infesting orange groves
at San Gabriel and Los Angeles, California. At first these were
described by Comstock as a new species, but after receiving copies of
Maskell's papers, giving the description of Chrysomphalus aurantii, and
upon receiving specimens from New Zealand, he concluded that they
were the same as those occurring there.
Regarding the occurrence of the scale in this state in 1880 Comstock
says, "I have observed this species in several groves at San Gabriel and
Los Angeles. At the first named place, where it is very abundant, it is
said to have first appeared on a budded orange tree which was purchased
by Mr. L. J. Rose, at one of the hothouses in San Francisco. At Los
Angeles it appears to have spread from six lemon trees which were
brought from Australia by Don Mateo Keller. Thus the question as to
the source from which we derived this pest is settled beyond a doubt.'
While it is undoubtedly true that this scale was imported into this
state directly from Australia, its native home can apparently be traced
further back than our acquaintance with it there. It is now supposed
that China is the native home of the red scale, though this is not posi-
tively established. The San Jose scale, Aspidiotus perniciosus was sup-
posed for a long while to have had its origin in Chile or Australia, but
later investigations showed that it had been introduced into both of these
countries, and it was not until an exploration was made of the Orient
that Marlatt' finally decided that China is its native habitat. So in the-
case of the red scale, it appears to have been introduced into Australia.
and that it existed for centuries before in some of the Oriential coun-
tries. That China is the native home of the San Jose scale is further
borne out by its relationships and distribution as an insect of temperate
regions. But in the case of the red, the relationships and distribution
are that of a tropical or semi-tropical insect rather than one of tem-
perate regions.
Maskell N. Z. Trans. XI, p. 199 (1878).
Can. Ent. XIII, p. 8 (1881).
U. S. D. A. Rep., p. 294 (1880).
'Marlatt Bulletin 62, Bur. Ent. U. S. D. A., p. 10 (1906).
FIG. 1.-Map showing distribution of Red Scale over world.
BULLETIN 222] THE RED OR ORANGE SCALE. 101
DISTRIBUTION.
Over World. The red or orange scale is very widely distributed over
the world, as shown by the accompanying map. It will be noticed that
it is largely a tropical or semi-tropical insect. New Zealand represents
the most southern location with a south latitude of 45 and New York
the most northern point with a latitude of 450 north. But the red scale
is not a pest in New York, and we are not sure but that this is simply a
greenhouse or incidental locality. While it occurs in New Zealand at a
latitude of 450 south there is here really a semi-tropical climate, for
I i
/ *
o N
citrus fruit areas of California. o represents C. aurantii; x represents
C. aurantii var. citrinus.
citrus trees are grown. According to Dewar', this scale is the most
important citrus fruit pest in the Orange River Colony. In West
Australia it is also considered the most serious scale of citrus trees. It
also occurs as a citrus pest in Cape Colony and other localities where
citrus fruits are grown.
'Ann. Rep. Ent. Orange River Colony.
UNIVERSITY OF CALIFORNIA-EXPERIMENT STATION.
The following places are recorded as having the red scale: Mauritius.
Ceylon, India, S. Europe, Syria, Natal, Cape Colony, China, Japan,
Australia, New Zealand, Java, New Caledonia, Samoa, Fiji, West Indies.
Greece, Turkey, Italy, Spain, Singapore, New York, Ohio, Florida, and
California.
In California. While the red scale is recorded from many other food
plants than citrus trees, in this state it is limited as a pest entirely to the
citrus, so that its distribution is governed largely by this host plant. In
the citrus area south of the Tehachapi, this scale occurs in the following
counties: Santa Barbara, Ventura, Orange, Los Angeles, Riverside, San
---- -- ---- --- - -- I
SANTA i ---SAN
BARBARA iVENTURA\ BERNARDINO
aO ,,'5" \ LOS ANGELES
% .. ./ L A n ,. i ,,X ... o '"-',--- "
6 / RIVERSIDE
SAN
DI EGO
FIG. 3.-Map showing distribution of Red Scale over southern California
citrus belt.
Bernardino, and San Diego. In Tulare County it occurs on citrus trees
in the city of Visalia, but has not yet reached the commercial citrus
section of that county around Porterville, Lindsay, and Exeter. It has
been noted in abundance on orange and ivy at Selma in the San Joaquin
Valley. It does not occur, so far as known, in Butte County, the citrus
section of the Sacramento Valley. Here its place is occupied by the
variety citrinus.
ECONOMIC IMPORTANCE.
The red scale is the second most important insect enemy of citrus
trees in California. In fact, a good deal of evidence may be submitted
for its claim to first place. If the yellow is included, which is justifiable,
THE RED OR ORANGE SCALE.
since it is only a variety of the red, the total amount of control work
directed against these would nearly, if not quite, equal that against its
competitor for first place, the black scale. The black is more generally
distributed, and has first place in most, if not all, of the coast counties.
In the case of other scales occurring with the black, the black is usually
considered as the least important when it comes to fumigating, since they
are, if in the proper stage, more readily killed. For this reason the
FIG. 4.-Tree partially killed by Red Scale.
black is sunk into second place, whereas, if left untreated, would prob-
ably cause more injury than the one which the treatment was especially
directed against.
The red scale ranks first as a citrus pest in Riverside and San Ber-
nardino counties, two of the great citrus producing counties of the state.
It also holds second place in Los Angeles and Orange counties, two other
BULLETIN 222J
UNIVERSITY OF CALIFORNIA-EXPERIMENT STATION.
counties where the citrus industry is of first importance. In San Ber-
nardino County about $200,000 is spent annually for fumigation and
$10,000 more for spraying to control citrus fruit pests. In Riverside
County $75,000 is spent annually in fumigation and $8,000 in spraying
for the same pests. While all of this is not directed against the red scale,
the majority of it is, since in these two counties the red is the most
injurious pest.
Fic. 5.-1 Red Scale on lemon. 2 Red Scale on nightshade.
on twig of lemon.
3 Red Scale
No citrus scale in California so quickly and so permanently injures
the tree as the red scale. The black seldom, if ever, kills a tree, its chief
injury being due to the sooty mold fungus on the fruit. The purple
often kills but a few of the lower or interior branches. But practically
the entire tree may be killed by the red, sometimes in one or two years'
infestation. It infests all parts of the tree, leaves, branches, fruit. It
not only causes a dropping of the leaves, but actually kills large
branches. Aside from this permanent and serious injury to the tree,
the presence of the scale on the fruit renders it unmarketable. Trees
that do not have a severe infestation of the scale, and where the tree
itself is not seriously injured, may have its fruit badly infested by the
scale.
I 'V3
THE RED OR ORANGE SCALE.
No honey dew is given off by the red scale, so that the characteristic
injury by the sooty mold fungus, as occurs with the unarmored scales,
is not present in the case of the red. The injury is due directly to the
feeding of the scales themselves, and, aside from their feeding, the fruit
is marred simply by their presence.
The injury by feeding is due to the loss of chlorophyl, toxic effect on
the tissues of the plant, and interference with the functions of the
stomata when the scale is abundant. Some scales have a much more
virulent poisoning effect on the tissues than others. One of the most
marked in this respect is the San Jose scale Aspidiotus perniciosus
Comst. On the fruit of apple or pear it causes a distinct reddening of
the surface tissue. If the bark be cut off where this insect is present
the deeper tissues will be seen to have a blackish red color. With such
insects the presence of a few will noticeably injure the tree. In the case
of others, such as the Greedy scale, Aspidiotus rapax Comst., the tree
may be completely incrusted with them, yet the tree suffers no noticeable
injury. It is only necessary to notice infestations of this scale on acacia,
laurel and others to see how abundant they may become and still the
tree appears normal. There is, to be sure, some injury done here, but
it must be largely on account of loss of sap, and where the tree has plenty
of moisture it can withstand a considerable drain in this respect. If the
same number of San Jose scales were to infest a tree as often occurs with
the rapax on acacia, laurel and others, the tree would be entirely killed.
So with the red on the orange, a heavy infestation on the twigs and
branches, as well as on the leaves and fruit, means the destruction of the
tree.
FOOD PLANTS.
While the list of food plants of the red or orange scale is large, it is
restricted very largely as a pest, to citrus trees. It is recorded from a
number of deciduous fruit trees, but is not a serious pest on those trees.
Most of the other food plants are ornamental, and pests on such plants
never rank in importance with those on commercial fruit trees. Here
in California the red scale is practically unknown away from the orange
or lemon. It does, of course, get on to several different kinds of plants.
but from an economic standpoint it is of little consequence excepting on
the citrus. It frequently happens that other trees, near by citrus trees
badly infested with this scale, will be infested to a greater or less degree;
but it is not often that such trees or plants are permanently infested,
and they seldom become serious enough to warrant treatment. The
problem of controlling the red scale, then, is limited practically to citrus
trees. In this respect the black scale presents a different situation.
Outside the citrus groves, three very important host plants, olive, ole-
BULLETIN 222]
UNIVERSITY OF CALIFORNIA-EXPERIMENT STATION.
ander, and pepper occur abundantly and everywhere in southern
California. One of the food plants, aside from the citrus, that is import-
ant from a control standpoint is the nightshade Solanum douglassii.
This weed occurs in waste places and also among the trees in the grove;
but the presence of this plant in a grove usually means neglect in
cultivation or care of the trees. These plants, growing as they do under
and among the trees, may be a source of reinfestation after fumigation.
The castor bean is another common native plant attacked, but it is not
generally in such close proximity to citrus trees.
The complete list of food plants from which the red scale has been
recorded is as follows: orange, lemon, cocoanut, fig, olive, agave, plum,
lignum vitT, buxus, Euonymus, Pistacia, rose, pear, quince, apple,
willow, oak, grape, acacia, tea plant, Podocarpus, wattle, Ligustrum.
Artocarpus, sago palm, nightshade, English walnut, eucalyptus, cam-
phor tree, Kennedya, passion flower, fuchsia, Bidens, Solidago, date
palm, California palm.
DESCRIPTION OF THE STAGES.
First Larval Stage. Length .24 mm. Greatest width .15 mmn. Color
sulfur yellow. The pygidium has two central lobes well developed and
conspicuous. Arising from each of these on the inner and dorsal sides
is a spine .25 mm. long; also a small spine
on outer basal margin. The median lobes
-_ are similar in shape to those of the adult
female, that is, they are abruptly narrowed
at about one half their length. There is but
a slight indication of a second pair and the
third is not present at all. There are two
plates between the two median lobes and
Also two between the first and second. Be-
yond the second lobe are from three to four
l I! short plates. The antenna consist of four
i' indistinct segments of the following com-
parative lengths 4-2-2-14. The fourth
is conspicuously annulate. There are six
FIG. 6.-Motile young of Red spines arising from the sides of this segment
Scale. x175. and two at the extreme tip. The tarsi have
a single claw, and there arises from the end of the tibia and extending
to or beyond the tip of the claw three of four nobbed hairs.
Second Stage Female. After the first molt the scale increases to
about twice its original size, and now all the characters of the pygidium
are distinct, but the legs and antenna, are lost. There are three pairs
THE RED OR ORANGE SCALE.
of conspicuous lobes with a spine arising from the base of each.
Between the two median lobes and between those and the second are
two conspicuous plates and three between the second and third lobes.
Beyond this are three additional plates. All the plates are deeply
fringed. There are no spinnerets.
The Adult Female. The average dimensions are about .78 mm. wide
and 1 mm. long. The lateral margins of the body extend downward
often as far as or beyond the tip of the pygidium.
The pygidium presents the following characters: There are three
pairs of conspicuous lobes, each notched at about one half their length,
making the distal half narrower than
the basal. On the dorsal surface there
is a spine accompanying each lobe. /
Those of the first pair are long and -
slender and situated at the outer
basal margin, so placed that they may
move either to the ventral or dorsal
side of the lobes. On the other lobes
there is one shorter and more blunt
spine arising from the middle of the -
base of the lobe. On the ventral sur- .
face the first pair of lobes have the FIG. 7.-ventral view of Red scale.
same spines, mentioned above in con- xo0.
nection with the dorsal surface. On the other lobes are each a single
spine situated in the middle at the base of the lobe corresponding to
those above. There are two plates between the first pair of lobes, two
between the first and second, two between the second and third and
three beyond the third lobe. The first plate beyond the second lobe
and the three beyond the third are deeply bifurcated and fringed on
the lateral margin.
The dorsal surface of the pygidium shows a number of dorsal tubular
spinnerets and several marginal spinnerets, as shown in the figure. It
will be seen from this that they are not arranged uniformly on both sides
of the median line. Near the upper margin are five curious shaped
structures with a couple of blunt pointed prominences projecting
anteriorly. On the ventral surface the vaginal cleft is shown, see figure,
with its radiating lines. The tubular spinnerets may be faintly seen
from this surface by focusing downward.
The Second Stage Male. There are no distinguishable differences
between the sexes until after the first molt. After the first molt the
male becomes more elongate or pyriform, as indicated by the follow-
ing measurements: average length .7 mm., average width .4 mm. The
BULLETIN 222]
UNIVERSITY OF CALIFORNIA-EXPERIMENT STATION.
pygidium characters are the same as in the second stage female. There
are two pairs of conspicuous purple eyes, one pair on the lateral anterior
margin, while the other pair is more dorsal and are nearer together.
Small spines arise from around the lateral margin.
The male propupa is orange yellow in color with the eyes very dark
red or brown. Length .7 mm., greatest width .35 mm. Dorsal eyes are
just posterior to antennal sheaths and in hollow formed by them. The
ventral eyes are larger and closer together and a little more posterior
than the dorsal. The sheaths of the antenna and wings are visible, and
a faint indication of those of the legs. But they are all more rudi-
mentary and lie closer to the body than is the case in the next stage.
There is no style present, but in its place is a blunt protuberance from
which arise two distinct spines. The truncate posterior end with the
button at the tip is the most evident character distinguishing this stage
from the true pupa.
The male pupa is of the same general color as the propupa. Length
exclusive of the style is .7 mm. The style is .1 mm. Greatest width
.32 mm. The ventral eyes are large and almost touching each other.
FIG. 8.-Stages of the male of the Red Scale. 1 Second stage. x56. 2 Pro-
pupa. x70. 3 Pupa. x70.
They are situated a short distance from the anterior margin. The dorsal
pair of eyes are wider apart and somewhat closer to the anterior margin.
The sheaths of the antenna wings and legs are evident and ordinarily
lie close to the body along the ventral margin.
The adult male has a wing expanse of 1.5 mm.; length exclusive of the
style .6; style .22; color orange yellow; antenna 10 jointed, the first two
segments being much shorter and thicker than the others. The com-
THE RED OR ORANGE SCALE.
parative lengths beginning with the proximal one are as follows: 5-4-
17-20-20-20-18-15-13-17. Total length .5 mm. The antennae
are light colored with some
yellow pigment. On all the
joints excepting the first two
are rather long hairs. The
lateral pair of eyes are dark
brown and situated just lat-
eral of the antennae. The -
ventral pair of eyes are much
larger and closer together and .
situated more posteriorly.
The legs, excepting coxa / 1
which are yellow, are glassy FIG. 9.-Male of Red Scale. x40.
white, and the tarsi light
brown. The thoracic band is of a light brown color. The halteres are
club-shaped, with the slender hook arising from the tip of the club.
LIFE HISTORY AND HABITS.
THE ACTIVE LARVA.
The red scale is viviparous, hence the starting point in the life history
is with the active larva, which are born alive. This means that what
ordinarily corresponds with the egg hatches within the body of the
parent, instead of the embryo developing and the eggs hatching outside
the body of the parent. Very rarely there appears an object that looks
very much like an egg. There are no free appendages or other char-
acters common to the young insect. But if this is placed under a
microscope or examined closely with a lens it will be seen that there is
a perfectly developed young insect within which is surrounded by an
enveloping membrane-the amnion. This encloses the developing larva,
and ordinarily is cast off within the oviduct, but occasionally, as inti-
mated, this is not cast off until it is outside the oviduct. The larva
emerging from beneath the parent scale, where it may have remained for
a day or two after birth, crawls about for a day or two longer before
settling and becoming fixed. It is most usual to find them settling on the
following day, but if, in the mean time, a suitable place for becoming
stationary and obtaining food is not found, they may remain active for a
day or two longer. They do not as a rule migrate very far from their
parent scale. Several oranges, badly infested with red scale which were
producing young, were each placed in a young orange tree that was
entirely free from scale. Two or three weeks later those trees were
examined to determine if any had settled on the tree. Hundreds of
young scales with their white circular covering were found, and imme-
BULLETIN 222]
UNIVERSITY OF CALIFORNIA-EXPERIMENT STATION.
diately about the fruit for a few inches the branches and leaves were
simply peppered with young scales. As the distance from the point of
liberation increased the number of scales decreased, and the maximum
distance they were found to travel and become fixed was 19 inches above
on one tree and 21 inches below on another. The tree was succulent and
thrifty and offered suitable ground for settling without much crawling
about. In other cases they are, of course, likely to go farther, and, in
addition to their own powers of traveling, they may be distributed about
by other insects. A fuller discussion of the subject of locomotion is given
under the head of "Locomotion and Spread."
Temperature and humidity records covering period when most of the life history data
on Chryso phalus aurantii iccrc secured.
Humidity (means). Temperature.
Menn T Mean
7 A. M. 12 M. 5 P. M. milnitmumn. maximum.
1909--Fbruaary -------- ..- 91 65 80 44 73.2
March ---- _____ 84.4 62 74.9 45.6 76
April 83.4 56 69 50.7 80.1
Ma\ y 83 57.7 66.5 53 81.3
June .--- ----- 83.5 63.4 65.9 57.1 84.2
July -- 85.4 59.9 68 59 87.1
August ------_ 82.6 50.1 59.1 57.2 93.1
September ---------- 85.4 56.1 72.5 58.9 90.8
October ------- ------ 83.1 55.2 75.5 52.8 84
November -- ------ 83.1 58 78 45.9 75.8
December 81.6 74.9 80.6 44 73
SETTLING OF THE LARVAE.
A few larva will settle down on the same day of emergence, but the
great majority will be found to settle on the following day. Daily records
of emergence were made on about 1000 scales, and out of this number
they would be occasionally found to settle before examination on the
following day. Records kept on 884 young larvm liberated in leaf cages
showed that about 95 per cent settled within one day. But here the
lhrva were picked from infested fruit as they were actively crawling
about, so that some may have been emerged for some time.
The proportion settling and becoming established in our cages was
41 per cent. These were liberated on leaves and had practically normal
conditions. The fact that they were enclosed in cages and thus protected
from enemies or becoming dislodged and falling to the ground, was
really in favor of a greater number becoming fixed than would be the
case were they out in the open. The insects were transferred by a small
camel's hair brush or a needle. Possibly some may have been injured in
the transfer, but care was taken in this regard, and usually the count of
the number liberated was made of those actually crawling about and
unharmed in the cages.
BULLETIN 222] TIE RED OR ORANGE SCALE. 111
The following table shows the number that settle, and, since these
experiments were extended over several months of the year, there
appears to be little effect due to season:
Date. a5 D Date.a a
1908-September 21 ----- 10 4 1909--September 22 -- 20 11
September 23 __-- 20 1 5 September 22 __---- 15 5
September 23 ----- 20 11 September 30 ________ 3 2
September 23 ----15 5 October 1 ----- 12 9
November 24 _--- 13 i October I ----- 7 5
1909-January 30 __-----.--- -- 1it 5 October 4 ---------------- 5 5
June 19 .. ..___- - .... ) 30 14 October 5 --- -- 12 12
June 19 _-2 ....- __- __.-- 30 13 October 11 ---- __ 8 5
July 2 __.________-------. -- 25 6 October 11 ----- 13 4
July 2 ---- 25 8 October 11 ---- 12 6
July 2 2___. ...- --- - 25 8 October 13 _____ __ 11 5
July 3 -_______30 10 October 14 -- __- 5 4
July 21 ._--- --- 20 7 October 20 ~_-- 9 4
July 24 _-- __- -- 20 5 October 20 __ ______ 6 3
August 12 9 4 October 21 ------------------ 6 2
August 13 - 20 5 November 26 12 5
August .18 ----- 14 11 1910-May 31 ----- --- 10 4
August 18 --_. ---- 14 10 May 31 ___.-- -__ _- 10 2
August 18 ----- 6 2 May 31 ____-___ 10 4
August 21 __ --__- 7 4 June 3 ._____ __ -10 5
September 2 ______ 14 6 June 6 ____ ______ 10 4
September 2 ____ 10 6 June 6 ___________ 10 3
September 3 ----_ 11 9 June 17 ___- --- 10 2
September 3 14 4 June 17 _.--- 25 6
September 4 _____-_ 6 3 June 20 __________ 7 2
September 4 ______- 15 6 June 20 ________9 6
September 7 18 5 June 20 -------- 11 4
September 7 _____ 20 5 June 20 ____-- 12 6
September 22 -__._- ... .--- 15 7 June 20 ______--_ 11 2
September 22 ___ 18 7
September 22 _-__-__-- 18 8 Total ---------- 884 363
September 22 20 13
September 22 __..______.. 16 8 Per cent settled, 41.06.
They may settle either on the leaves, branches or fruit. It seems to
make no very great difference where they settle so long as it is con-
venient. But the part of the tree that is more likely to be severely
infested first is the branches, later the leaves, and finally the fruit.
They will be found on both sides of the leaves, but the upper side,
usually, has the greater numbers. In the case of the yellow it is more
often the under side. The red will not settle readily on the older and
larger corky branches, but prefer the younger succulent branches where
not so much of the corky material has been deposited.
FORMATION OF THE SCALE COVERING.
When the active larva first settles the legs and antenna are withdrawn
beneath the body and in an hour or two a cottony secretion appears
from numerous pores over the body. In another hour a light flimsy
covering of cottony threads envelops the entire scale and extends down
over the sides of the insect to the surface on which it is resting. The
2-BUL. 222
UNIVERSITY OF CALIFORNIA-EXPERIMENT STATION.
FIG. 10.-1 Different stages in formation of scale covering. 2 The
ventral scale formed beneath the insect. 3 Old and young red
scales on orange. 4 Larva of parasite, Aphelinus diaspidis, feed-
ing on Red Scale; the scale shriveled from absorption of body
contents. 5 Yellow scale containing pupa of parasite Aspid-
iotiphagus citrinvs.
! I r IffPf 11,
THE RED OR ORANGE SCALE.
covering is still transparent enough to see plainly the insect beneath.
By this time the insect itself has shortened in length, while its width is
increased, and it thus becomes almost circular. While this covering is
being secreted the insect beneath revolves about for the purpose of
molding the covering in the proper form.
It is generally assumed that the insertion of the beak into the plant
tissue is a necessary preliminary operation to the secretion of the cover-
ing. On this point our observations, in general, seem to agree, but the
actual operation of inserting the beak can not be seen readily. They
have been seen to settle with the beak inserted and then withdrawn
again before any covering is started. The withdrawal of the beak has
been noted in a few instances, and the process is characterized by more
distinct indications than is the case with the insertion. A considerable
movement of the body occurs by turning partly around, and also a rapid
movement of the legs and antenna. Certain cases have been observed
where the young scales settled on top of an old one and secreted the
preliminary covering, yet the depth of the old scale was too great to
allow the young one above to reach the plant tissues. In such cases the
covering is commenced before the beak is inserted or at least before any
food is taken. It often happens, of course, that young settle on the
outer margins of the old scales, but here there is no difficulty in reach-
ing through to the plant substance beneath.
The same insect may secrete a new covering for a few times if the
old one is removed. A scale covering, one or two days old, was lifted
from the insect and again replaced. It accepted the new covering, and
four days later it was again lifted, and again replaced. This time the
covering was not accepted, but a new covering was secreted. In the case
of other insects the covering was permanently removed, and the maxi-
mum number of new coverings formed was four. When the covering
was removed three or four times or more the insect died.
A couple of days after settling the covering is more compacted,
especially on the sides near the surface upon which the insect is resting.
The dorsal surface is still light and fluffy, but thick enough to entirely
conceal the insect beneath. The form at this time is that of a cap with
a flat dorsal surface and straight vertical sides. After a few days this
sinks down immediately around the center leaving a small prominence
forming the so-called nipple. As the scale covering increases in size, it
spreads out with a thin edge forming the margin instead of the vertical
wall as was the case earlier. In a week or two all the cottony effect is
lost, and the covering becomes a very compacted film. In eighteen to
twenty days the cast skin of the insect may be seen incorporated into
and forming the greater part of the covering. With the increased size
of the insect after the molt it becomes necessary to enlarge the covering.
BULLETIN 222]
UNIVERSITY OF CALIFORNIA-EXPERIMENT STATION.
and this is extended beyond the cast skin, which soon comes to form but
the center of the scale covering. A similar cast skin is incorporated
into the covering after the second molt which is about twice the size of
the first. Thus the two cast skins may be seen forming two nearly
concentric circles. The covering is again extended, being secreted and
added to the outer margin until the total width may be twice that of
the second cast skin. During this formation of the scale the lobes and
plates of the pygidium play an important part in molding it into the
proper form. The insect during the process, must revolve around to
reach the margin with the posterior tip of the body which is capable of
being greatly extended or contracted as required.
FIG. 11.-1 Scale of male. 2 Scale of female, same magnification. 3 Inverted
male scale, showing winged insect beneath.
The above account has reference to the female scale only. The scale
of the male is exactly the same until after the first molt, but from that
stage on it takes on a very different form from that of the female. The
male insect itself during the second stage becomes much more elongate
and so the scale covering assumes a corresponding shape. After the first
molt the male scale covering widens but little, but increases consider-
ably in length, so that the mature scale is about twice as long as broad.
But its extreme length is not as great as the diameter of the mature
female scale. The average size of the mature female scale is about
1.5 mm. in diameter, while the mature male scale is about 1 mm. in
length.
THE FIXED YOUNG.
Molting. After the insect has settled and the covering secreted it
undergoes no change, except to increase in size, until after the first molt.
This molt occurs in from fourteen to twenty days after settling. Prelim-
inary to molting, the insect, which, up to this period is readily separated
from the scale now becomes firmly attached to it. Previous to this time
the body of the insect has a flexible, and somewhat tough covering, and is
24 1
THE RED OR ORANGE SCALE.
not much distended by the contents. But during the molting period,
which lasts from three to five days, the body wall is hard and brittle
and well distended. The body contents seem to be much more fluid and
eatery during this period. This change in the body wall and its con-
tents is shown during
the handling of the
insect with a needle.
Between the mo 1 ts
punctures are less
likely to occur for the
reason of the flexibility
of the skin, while it is
very readily punctured
through the firm dis-
tended skin during the
molts.
The skin is split
around the lateral mar-
gin, not only around
the general body mar-
gin, but often the mar-
gin of the lobes and
plates also. If the cast
dorsal skin be treated
in potash the lobes,
plates and spines show
nearly as clearly as in
the insect itself in
some of the specimens.
If the very frail and
7<~~n J ~ ,
xx rv"[9!
l i -,l-- /2
V1
5i
/ i i
(L ~4
I,
j .1
' /,"
I.
\-' ; '-; /
i '
Fi. 12.-a Dorsal view of pygidium of Red Scale,
x200.
b Ventral cast skin of Red Scale. From same in-
sect as Fig. 13, 3, which is the dorsal cast skin.
almost invisible cast ventral skin be examined most of the pygidial
characters will also be seen in some of the specimens. Some times
greater detail of the pygidial structures is shown in the ventral and
some times in the dorsal cast skin. The figures Nos. 12 and 13 indicate
this. In the first ventral skin the legs, antenna and mouth parts are
of course present.
The molting of the male differs very strikingly from that of the
female excepting the first molt which is the same in both cases. Instead
of the skin splitting around the lateral margin as is the case with the
female, the rent occurs near the anterior end, and the old skin is pushed
backward and from under the scale. These cast skins may often be seen
still attached to the posterior tip of the scale.
BULLETIN 2221
UNIVERSITY OF CALIFORNIA-EXPERIMENT STATION.
FIm. 13.-1 A cast skin after first molt. 2 A ventral cast skin, second molt.
3 Dorsal cast skin. second molt, same insect as Fig. 12, b, which shows
the ventral cast skin. 4 Characters of complete insect. x350.
,';. 14.-Showing the mature Red Scale with its cast skins
and the scale covering. 1 First cast skin. 2 Second cast
skin. 3 The insect itself. 4 The scale covering. x60.
The second molt of
the male insect occurs
in about thirty days
from birth which
brings it to the pro-
pupal stage. It re-
mains in this stage
about ten days when
the third molt occurs
after which it is in
the true pupal stage.
Ten or twelve days
are spent as a true
pupa when it trans-
forms to the adult.
The adult remains
beneath the scale from
three to five days be-
fore emerging. The
shortest period re-
BULLETIN 222] THE RED OR ORANGE SCALE. 117
quired for the development of the male was found to be 55 days. This
was from June 20th to August 14th, which included the hottest weather
of the season of 1910. The longest period determined for the develop-
ment of the male was 112 days. This was from January 2 to May 1,
1909, which included the coldest weather of the season.
THE ADULT MALE.
The male pushes its way backward from beneath the scale and actively
walks about immediately after emerging. Upon transforming to the
adult it remains beneath the scale for a few days, so that the wings are
thoroughly dried and expanded, and is at once strong enough to begin
its short period of active life. It usually walks about on the leaf or
fruit for a short time, and then flies away. This appears to be a provi-
sion to insure the fertilization of females some little distance away, and
thus prevent possible degeneration through in-breeding with the females
of the same parent which usually settle down in the immediate vicinity.
Copulation may occur within a half hour or hour after emergence. The
adult life varies from one to five days. The male of this, like most
other scale insects, is not a strong flier, but may be greatly aided in
prolonged flights by the wind. They appear to be more abundant at
certain seasons, and this is particularly true of the early spring. The
following table gives the proportion of the sexes according to the time
liberated which includes most of the months of the year. It will be
seen from this that during the first half of the year the number of
males was 74 while the number of females was 42. During the second
half of the year the sexes were approximately equal, the table giving 34
for the males and 35 for the females:
FIRST HALF-YEAR. SECOND HALF-YEAR.
Number Number Number Number
Young liberated. males, females. Young liberated. males, females.
January 2 7 1 3 August 18--- 2 2
February 24 ------ 1 September 2- 2 1
May 12---- 7 4 September 3 --- 2 1
May 13 ..---- 22 8 September 7.--- 1 1
June 3------------ 5 3 September 22-- --------- 7 2
June 4-- ----- 3 3 September 22 -----_- 1 1
June 7---- 7 4 October 5------ 5 5
June 17- 5 3 October 11.-- __---- 4 2
June 17_---- 2 1 October 13------ 0 3
June 17------ 2 3 October 14 ---- 2 1
June 18 -------2 4 October 20 ------ 1 2
June 18--- --- 2 1 November 10- ----- 2 4
June 19 ------- 0 3 November 29-- __ 0 3
June 19 ------ 2 0
July 24 ------- 4 1
Total ----- -- 74 42 Total ----- 34 35
UNIVERSITY OF CALIFORNIA-EXPERIMENT STATION.
THE ADULT FEMALE.
The second molt of the female occurs from 40 to 50 days after birth,
which brings it to the adult. It continues to secrete the scale covering
after this molt to allow for its increased growth. From 10 to 20 days
after the second molt it is fertilized by the male. This is on an average
about 60 days from birth. The formation of the scale is entirely com-
pleted before the production of young is commenced. During the
period the insect is producing young it is similar to that of the molting
periods. That is, the insect itself is inseparable from the scale, and the
body is rigid and distended.
LENGTH OF ADULT LIFE.
The female scales begin to produce young in about ninety days, and
this is continued from one to two months longer, making the total life
of the adult from four to five months. In case the female is not
fertilized the adult life may be extended much longer. Five females
FIG. 15.-Red Scale, mature females and young.
isolated in cages were perfectly healthy and vigorous and not yet having
produced young after a period of five months and twenty-six days.
This was during the warmest part of the season, from May 31st to
November 25th, when cold was not a factor in retarding development.
This fact was learned in connection with the experiments on partheno-
genesis. When insects liberated at the same time were fertilized and
had completed their production of young the leaves containing the
unfertilized scales were unfortunately removed from the tree for exam-
ination. This prevented us from obtaining the maximum life of the
THE RED OR ORANGE SCALE.
unfertilized female, and also from determining if they could, at that
late date, be fertilized and still produce their quota of young. This
latter fact will very probably be true, but as yet the evidence of actual
trial is not at hand. In case the female is not fertilized it thus appears
that its development is practically at a standstill for at least three
months, or it will live for at least three months after reaching maturity
without producing young.
AGE AT WHICH YOUNG IS PRODUCED.
The minimum period from birth to the appearance of young was
found to be 73 days. This was from June 20th to September 1st, which
included the warmest weather for the season of 1910. This was at
Riverside, where the temperature is higher than that of Whittier, where
the most of the work was done. Parallel experiments carried on during
the same period showed the minimum period from birth to the produc-
tion of young as 81 days at Whittier.
The maximum period was from February 24th to June 30th, or four
FIG. 16.-Red Scale (Chrysomphalus aurantii Mask.) on grape fruit.
months and ten days. Young born on January 2d did not produce
adult males until May 1st. Allowing the usual thirty days from fertil-
ization to the appearance of young would make a period of five months.
BULLETIN 222]
IZU UNIVERSITY OF CALIFORNIA-EXPERIMENT STATION.
This represents the maximum for the coldest weather of the season.
The age at which young is produced is also dependent upon the time of
fertilization. Scales may live for four or five months during the
warmest part of the year, and then after fertilization very probably
produce young.
ASPIDIOTUS AURANTII--DEVELOPMENT.
u peri-
tlient Date Settled.
at.umiter
1-4_- 9-23-08 9-24
33_- 1- 2-09 1- 3
104__' 2-24 2-25
102-1 2-20 2-21
106-_ 2-24 --
139- 5- 4 5- 6
146_ 5-12 5-13
149-. 5- 9 5-10
150I.- 5-19 5-21
151_ 5-19 5-20
161.. 5-21 5-23
148__ 5-13 5-14
173__ 6- 4 6- 5
182 6-17 ----
183-! 6-17 -
184.. 6-17 6-18
187__ 6-18
1M89-. 6-18 ----
1900- 6-19 --
19P1 6-19 ----
192! 6-19
193--_ 6-19 --
215 __ 7- 2 7- 4
214 7- 2 .
217..- 7- 3 --
256 7-21 7-23
260_ 7-24 --
279 -_ 8-12
285..- 8-12 8-13
3112- 9- 2
312___ 9- 3
322__ 9-22 ..--
323_ 9-22 -----
325 9-22 9-23
326- 9-22 ---
327--- 9-22 9-24
335-_ 10- 5
341 10-11 --
342- 10-11
347- 10-14 .
55I-_ 6-17-10 ..-
561 6-17 -----
56.3-- 3 5-1 -----
564__ 5-31 6- 1
568. 6-6
569- ---- 6-6
*570_1 6-20
*571__ 6-20 -
*572-- 6-20 --
*573- 6-20 --- -
Summary av __ 24 hrs.
*At Riverside.
Filrtt
ttiolt.
3-16
3-16
6- 4
6 -
1
7- 1
7- 3
7- 3
Second ecod Se Pruna io ELgergd
Ii.ilt molt' P Pttp.. o Dead. yoa.-
.----- ---- .------ 11-25 12- 1 1- 2-09
4-16 5-1 5- 5 .----
4-20 330 4-16 5-11 5-15 6-30
4-20 1 3-30 4---- 4- 8 ----
-- -2- --- ---- ----.- --- G-26
------ 6-28-------- 8- 6
028 . .. . .. . 86
... ..... 7- 3
6-15 6-30 .
7-10 ...- -... 7- 2
7-14
6-30 -. 6-22 ----
-- 7-12 7-21-----
7 27 7-21 ----
S 7-21
7-2 ----- 7-21 --
7-28 ---- 7-21
8- 1
7-14
Y~ I
7- 5 7-17
--- ... 7-17 -
--- -------- 8-11 8-24
7-171 --- 7-28 8-11 .--
S --- 8-11 8-24
8- 5 ---.- ----- 8-16 ..--
-.. -......- ---- _-------- --- -----8 -- --
.... -------- --. .--- 9-20
9-18 10-15 --- -------- 10-20
S0 10-1. ............... ... ....
9-20 ---- ------ -----
----- ----- --- --- ------ ----
---- 10- 5 10-18 10-29----
-- -------- 10-29 ------
10-12 11-6 ----- ---.
10-14 --- -- ---- 10-29
10-25 ------ -
---- - ----- -----
10-30 - - --
1------------ -------- -.
---- 7-20 7-16 7-28----
7- 3 -- ------ 7-21 --
- -------- -------- -------- -------
---- 1 7-27
-- 7-12 -..--
7- 4 .. .. -...... __ ........
7- 4 ------- --- -
16 days 46 days 30 days 38 days 48 days
7-14 ---- --
7-18 7-22 8-10
7-21 -----. 8-18
7-21 -
7-21 7-26 8- 7
7-12 7-16 ---
9- 8
- -- I ---- [
8-11 i -
8-11 8-16
8-11 ----
8-11 8-15
9-10
8-14 -----| ---
---- -- 9-10
9-10 9-14 --
9- 9 ---- 10- 6
10-10 10-14 11-24
10-12 ----......- 11-27
10-29 11- 2 1-18-10
10-29 ....
12- 2----
12- 2 12- 6 -
11-30
12- 5 12- 8 ---
1- 2-10
1. .....
S1 -- :: : -- -- -- ---
1-11
1-15 1-20 -
1-27 ..--- I 3-25
8-4 -------
7-28
8-4 ----
8-14 9- 1
.. ...... 9- 2
8-14 ..---- 9- 1
60 days 65 days I 90 days
___
THE RED OR ORANGE SCALE.
EMBRYONIC DEVELOPMENT.
Since the female comes to maturity and is fertilized by the male about
sixty days from birth, and the production of young begins on an average
of ninety days, the time required for the development of the egg and
the hatching of the larva therefrom within the body of the female, is
about thirty days.
FIG. 17.-Greedy Scale (Aspidiotus rapax Comst.). Sometimes
mistaken for Red Scale.
PARTHENOGENESIS.
Several individual female red scales were isolated as they approached
maturity, and no males allowed to reach them. In every case no young
appeared under such conditions. These lived for a period of more than
six months, with no indication of young appearing. The insect remained
in the condition it was after the second molt, that is, it was free from
the scale covering and with a pliable body, as opposed to the gravid
condition or molting periods, or young-producing periods, as already
explained.
EMERGENCE OF YOUNG.
The emergence of young means practically the same as the birth of
young, but since the actual birth records can not be obtained without
destroying the parent, emergence is used in this discussion rather than
birth. This makes no difference in the total number, or the length of the
BULLETIN 222]
UNIVERSITY OF CALIFORNIA-EXPERIMENT STATION.
producing period, though it may make some difference in the rate from
day to day. That is, when a sudden drop in the temperature occurs,
for instance, the young already born may linger under the scale for a
longer period than would otherwise be the case. But the records given
show that there is little variation on this point. The maximum number
emerged in a single day was found to be eight. But five or six may
appear for three or four days in succession, showing that this number
must actually be produced on those days.
The records given in the table are for fourteen females, of which daily
examination was made throughout the producing period. Many other
FIG. 18.-Red Scale on orange leaf.
records were less accurately made. The period during which young
were produced varied from 16 to 63 days, with an average of about 23.
The number of young per insect varied from 34 to 143, with an average
of 55. The number of young appearing in a day was from 0 to 8. The
average number of young per day for the different scales ran from 1.65
to 3.07, with an average for the total number of scales of 2.33. These
records on the production of young were made during the months of
September and October mostly. September in southern California is a
fairly warm month, and during October it seldom gets cool enough to
have any marked effect on the activity of the scale. Records on the
emergence of young during June and July showed that it was prac-
tically the same as that of September and October. Those given, there-
fore, may be considered as a fair average for the active season from
April to November.
BULLETIN 222]
THE RED OR ORANGE SCALE.
EMERGENCE OF YOUNG.
NI N N -
B Date. 1010. 0 Date. 110. 0
80; 06 '06
4
3
Date, 1910.
Sept. 20 --..-
Sept. 21 -----
Sept. 22 ---
Sept. 23 ----
Sept. 24 ----
Sept. 25...
Sept. 2_6 --- |
Sept. 27 ---|-
Sept. 28 _---0
Sept. 29 ..--
Sept. 30 S---
Oct. 1 ---I-
Oct. 2 --..
Oct. 3 ----
Oct. 4 ---
Oct. 5 ----
Oct. 6 _---
Oct. 7 ----
Oct. 8 ---
Oct. 9 ..-
Oct. 10 ..
Oct. 11 -
Oct. 12 _....
Oct. 13 --_-
Oct. 14 -----
Oct. 15 ----
Oct. 16 ..--
Oct. 17 .
Oct. 18 ----
Oct. 19
Oct. 20 -
Oct. 21 ----
Oct. 22 ---..
Oct. 23 ----
Oct. 24 -
Oct. 25 .1---
Oct. 26 --
Oct. 27 -----
Oct. 28 --
Oct. 2-----
Oct. 30----
Oct. 31 ---
Nov. 1----
Nov. 2--
Nov. 3-----1
Nov. 4 -----
Nov. 5 --
Nov. 6 ---
Nov. 7 ----__
Nov. 8--- -;
Nov. 9 -----
Nov. 10 ---
Nov. 11 --
Nov. 12 ----
Nov. 13 ----
Nov. 14-1 -..
Nov. 15 -___- i
Nov. 16 -
Nov. 17 ----
Nov. 18 ----
Nov. 19 ----
Nov. 20-
Nov. 21 ---
4
Date, 1910. Date. 1910. Z
ai? \
25 .....
26-----
26 ..
27..---
28----
29-----
30 ...
20
S-..--
4--
5-----
-..---
8 .
10--.
11.
12
13
14--.
15 ---
16---
17 -----
18 .--
19
28 ---
29 ---
30 ---
21-----
1..
3----
4----
5 ---
6 ---....
7 ------
8 .----
9 ---
10--
11 ---
Total --. 143 Total
Days _-- 63 Days
Av. per day __.25 Av. per
--- 33 Total .
20 Days _-____
day-- 1.65 Av. per day_
64 Total --.. 89 I Total
26 i Days
25 i Days
2.46! Av. per day 3.56 Av. per day- 3.07
5 Sept. 21 --
5 Sept. 22-
3 Sept. 234
:l Sept. 24 --
2 Sept. 25 --
5 Sept. 26 --
4 Sept. 27-
0 Sept. 28 __
0 Sept. 29 --
0 Sept. 30 --
0 Oct. 1 --
2 Oct. 2
3 Oct. 3
4 Oct. 4 --
4 Oct. 5 --
0 Oct. 6 --
1 Oct. 7--
0 Oct. 8-
2 Oct. 9 ..-
6 Oct. 10 -
6
5
1
4
1
0
0
2
2
4
0
3
4
2
4
0
2
0
2
3
2
2
3
2
3
2
2
3
2
0
2
9
Sept. 24
Sept. 25
Sept. 26-
Sept. 27_
Sept. 28
Sept. 29_
Sept. 30
Oct. 1_
Oct. 2-
Oct. 3
Oct. 4_
Oct. 5-
Oct. 6_
Oct. 7-
Oct. 8_
Oct. 9
Oct. 10
Oct. 11
Oct. 12-
Oct. 13
Oct. 14_
Oct. 15_
Oct. 16_
Oct. 17
Oct. 18.
Oct. 19 .
UNIVERSITY OF CALIFORNIA-EXPERIMENT STATION.
EMERGENCE OF YOUNG-Continued.
Date, 1910. o Date. 1910. Date, 1910.
BP {&
Sept. 28 ----
Sept. 29 ----
Sept. 30 ----
Oct. 1 ..--
Oct. 2 -----
Oct. 3 -..-
Oct. 4 ----
Oct. 5 ----
Oct. 6 0---
Oct. 7 ---
Oct. 8 ----
Oct. 9 ----
Oct. 10 --
Oct. 11 .-..
Oct. 12 ----
Oct. 13 --
Oct. 14 ----
Sept. 29 ----
Sept. :0 ----
Oct. 1 ----
Oct. 2 ..---
Oct.
Oct. 4----
Oct. 5-
Oct. ( ----
Oct. 7 --
Oct. 8 --..-
Oct.
Oct. 10 ..---
Oct. 11 -.
Oct. 12 ..-
Oct. 13 ----
Oct. 14 --
Oct. 15 ..-
Oct. 16 .----
Oct. 17 ---
Oct. 18 .. -.
Oct. 19 -----..
Total ----- 57 Total --.
Days ...-- 17 Days --
Av. per day_. 3.35 Av. per day-.
2 Sept.
1 Sept.
0 Oct.
1 Oct.
1 Oct.
1 Oct.
3 Oct.
4 Oct.
3 Oct.
4 Oct.
5 Oct.
4 Oct.
3 Oct.
0 Oct.
2 Oct.
3 Oct.
2 Oct.
1 Oct.
0 Oct.
11 Oct.
1
29 ...
1 ......
2 -
3 -- -- --
4 ......
8 ----
9 ----
10 --
11 ..---
12 --
13 ---
14 ..---
15 ---
16 --.-
17......
18..__
r Date.
S7 Sept.
4 Sept.
5 Sept.
4 Sept.
S3 Sept.
4 Sept.
4 Sept.
4 Sept.
4 Sept.
4 Sept.
5 Sept.
6 Sept.
3 Sept.
0| Sept.
1 Sept.
0 Sept.
1 Sept.
0 Sept.
S 0 Sept.
2 Sept.
Sept.
Sept.
Sept.
Sept.
Oct.
Oct.
Oct.
Oct.
Oct.
Oct.
Oct.
Oct.
Oct.
Oct.
Oct.
Oct.
1910.
1 ...
2 --
7
9-
10 ---
12-..
13 ---
14 --
15 --
16 --
17 ..--
19-..-
20--
21--..
22--
23 --
24 ----
25--
26.--.-
27-..
28-..
29- .-
30-
10
01. ...
2 ..--
3 ---
4 ..--
5 ----
7..--..--
8 --..--
9 --..
10---
11--
12....
42 Total --- 61 Total --.-
21 Days -__--- 20 Days -
2 Av. per day.- 3.05 Av. per day
ig Date, 1910.
4 Oct. 1--_
4 Oct. 2__
1 Oct. 3---
1 Oct. 4---
1 Oct. 5---
1 Oct. 6--.
2 Oct. 7---
1 Oct. 8--
1 Oct. 9-.
0 Oct. 10--.
2 Oct. 11-.
1 Oct. 12--
0 Oct. 13-.
1
1
S 2
. 1
2
0
1
0
0
0
2
0
1
0
1
1
0
S 0
1 1
1
. 1
S 2
38 Total
42 Days ---
.90 Av. per d
ay_
ia~
ig
P~
BULLETIN 222]
THE RED OR ORANGE SCALE.
EMERGENCE OF YOUNG-Continued.
Date, 1910. B
October 1
October 2 ..
October 3 _---
October 4 .----
October 5 ---
October 6 -..
October 7 _---
October 8 --
October 9 __--
October 10 .----
October 11 __
October 12 --.__
October 13 __--
October 14 -----
October 15 ----
October 16 ..--
October 17 .--.
October 18 __--.
October 19 .._
Total -------
Days _-----_ _
Date, 1910.
October 1 _-
October 2 __---
October 3 ______
October 4 ____-
October 5 --..__
October 6 _----
October 7 -----
October 8 ---_-
October 9 __.--
October 10 ..--
October 11 ----
October 12 ---
October 13 ._.---
October 14 _..--
October 15 _..._-
October 16 ..-..-
October 17 ..--_
October 18 ---.i
Total _- ----I
1
0
0
0,
2
2
Date, 1910.
October 4
October 5 .---
October 6 ___
October 7 --
October 8 --__
October 9 --.-
October 10 .___
October 11 -
October 12 --
October 13 ____
October 14 --
October 15 __-.
October 16 ...
October 17 --
October 18 -.-.
October 19 _.._
2
3
37 Total
19 Days ----------- 18 Days
S Date, 110. 10
5 October 5 ----- 4
5 October 6 ...--- 6
16 October 7---
5 October 8 .5
6 October 9 ..-- 4
October 10--- 5
: October 11 -- 4
:; October 12 ----- 2
1 October 13 _- (0
I October 14 -- 1
S 1 October 15 0
0 October 16 -- 2
2 October 17 ___--- 2
2 October 18 -- 3
S 3 October 19 --.--: 3
1 October 20 ----' 4
S 50 Total -- 50
16 Days .---------- 16
Av. per day- .- 1.79
Av. per day 2.05 Av. per day---. 3.12 Av. per day--- 3.12
Grand total number of young -----
Number of days producing ----
Average number per day___-- ------
Number of insects -- -----
Average number young per insect ----
Average producing period, days-- __ ------.
771
3-30
2.33
14
-55
.- .--- 23.57
DO THE INSECTS MOVE AFTER BECOMING FIXED
The statement has appeared that the red and yellow scales, particu-
larly the yellow, may move after becoming fixed. This statement is
based upon no evidence, but upon the fact that there appears a distinct
streak of yellow tissue showing where the beak has been inserted, and
this being too long to be produced without some movement of the scale.
Several dozen scales, both red and yellow, were surrounded by India ink
to determine this point, but none were found to move in the slightest
degree. It was observed that in the formation of the scale it was
extended under the film of ink. The circle of ink on the leaf, which
just surrounded the young scale was later resting on the scale itself,
which had extended under and beyond the ink film.
Both the red and yellow scales, but especially the yellow, often pro-
duce a yellowish spot about the point of puncture. This often shows
through on the opposite side of the leaf. Sometimes this spot is much
larger than the scale itself. It may appear in a uniform circle with the
scale as a center, and again, the discoloration may be all on one side.
The size, shape and position of the spot may thus vary considerably.
That the spot is due to the extraction of the chlorophyll from the cells.
UNIVERSITY OF CALIFORNIA-EXPERIMENT STATION.
or from the toxic effect of the insertion of the beak, seems well estab-
lished. It is most usual for the yellowing to appear in circular spots,
and these areas may be much larger than can be reached by the beak.
That these areas should sometimes take on different forms, even to the
extent of a narrow streak, is not improbable, and it is hardly necessary
to take the movement of the scale into consideration to account for it.
Another point against any movement is the fact that the flimsy ventral
cast skins are always found directly beneath the mature insect. It is
scarcely possible that these would be pulled along with it.
SEASONAL HISTORY.
The average length of the life cycle from the active young to the
appearance of young again is about three months. During the warmer
weather it will run slightly under this, and during the coldest weather
it will run considerably more, the extremes being from 72 days to
nearly 150 days. Four generations a year will be the largest number in
a season. It is not unlikely that this number occurs in the warmer sec-
tions-as Redlands and Riverside. But in most sections three genera-
tions, with a partial fourth, will represent the actual conditions. Start-
ing with April 1st, the beginning of the next generation will be about
July 1st. Those young appearing at this time will be producing young
themselves by the first of October. This will make two generations
during the months of greatest activity. Those young appearing in
October may not, as our life history work has shown, give rise to young
again before February or March. This makes three full generations,
with a partial fourth, for conditions as they obtain at Whittier.
ANNUAL PROGENY.
It is a well known fact that citrus trees may become very severely
infested with red scale in a single year, and with a two years' infesta-
tion a large portion of the tree may be killed. This often happens after
the grove has been fumigated, and it is charged that the fumigation has
not been effective. This may or may not be the case. But even if the
fumigation has not been well done, if the scale is carried in from a
neighboring grove, the trees will be badly infested again within a year;
this is accounted for through the rapid multiplication of the insect.
While the number of young from a single individual is not nearly so
large as that of the black scale-not more than one fortieth as large-the
increased number of generations make the number much greater at the
end of the year. Counting the average number of young produced by
a single red scale at 55, and allowing one half of this number for males,
the number at the end of the third generation will be, more than 40,000,
and the number at the end of the fourth generation will be more than a
THE RED OR ORANGE SCALE.
million. These figures include the males, but since the males feed
during the first two stages, or for a period of thirty days, they must be
counted as injuring the plant, but of course not to such an extent as
the females. While, therefore, a black scale may produce forty times
as many young as the red, the progeny from a single red scale at the
end of a year, with four generations, will be five hundred times as many
as the progeny of the black, which has but one generation. Only a small
per cent of these, to be sure, actually comes to maturity, but it is an
indication of what might be approached if all conditions were favorable.
MORTALITY.
One of the most critical periods in the life of the red scale is during its
active larval period. Not only is it more exposed to the attack of enemies
of all kinds, but its own failure to become established is a serious check
on its numbers. The actual figures given earlier in this account show
that, under the favorable conditions of being protected from outside
agencies, the number settling amounts to but 41 per cent of those that
are active. More than one half is thus lost before they have scarcely
started on their life cycle. Many of those that do settle fail for one
cause or another to reach maturity. The molting periods are other
critical stages, and many fail to pass successfully through these.
Weather conditions may also be factors tending to decrease their num-
bers, but these are not so specifically isolated as in the case of the
influence of hot weather on the black scale. Parasites and predatory
enemies are other agencies that affect the number of the red scale in all
stages, but these will be discussed later.
LOCOMOTION AND SPREAD.
The red scale, like most other scale insects, is distributed over long
distances mainly through the interchange of nursery stock or the
marketing of fruit. This scale very readily attacks the fruit, and they
may live on this, as in case of the lemon, for many months after being
harvested. Professor Coit of this station wrapped a few lemons in
ordinary newspaper and stored them away in his house on December 5,
1909. These apparently had a few scattering scales which were not
noticed at the time of storing. On June 30, 1910, or nearly seven
months later, these were unwrapped, and upon examination were found
to be badly infested with the red scale. Altogether there were 35 adults,
and between 800 and 900 young, all alive. The adults were those present
when the fruit had been stored, and, at the time, were probably not
very fully developed. But they completed their development, and after
an interval of seven months young were still appearing. In this time
the fruit, had it been in transit, would have had time to reach most any
3--Bu. 222
BULLETIN 222]
UNIVERSITY OF CALIFORNIA-EXPERIMENT STATION.
FIG. 19.-Tracings showing actual movement of motile young red scales for
a two-hour period. Reduced seven times. 1 Temperature 660; average
distance traveled, 31 inches. 2 Temperature 910 ; average distance 111
inches.
r4-.
f -
THE RED OR ORANGE SCALE.
part of the world. An interesting point with these scales was that they
were very light gray or grayish white in color, and were mistaken at
first for the greedy scale (Aspidiotus rapax). This striking difference
in color from the usual red must be accounted for from the absence of
light, since they were securely wrapped in paper during all the period.
The spread of the red scale over the same general community is
effected largely by birds and active insects, together with the agency of
man in his usual cultural operations. In the spread from tree to tree,
aside from the above factors, the power of the insect to transport itself
is entitled to consideration.
Rate of travel over smooth surfaces. With a view to determining
how far a red scale would travel under the most favorable conditions,
records were made for two hour periods on smooth paper. When the
temperature was 660F. four active young red scales traveled 23, 25.5,
34, and 41 inches, respectively, or an average of 31.12 inches. Under
the same conditions, when the temperature was 910F., the maximum
distance traveled was 111 inches, or more than three times the distance.
Several other experiments on the rate of travel over paper showed
similar results.
A young red scale is active for from twenty-four hours to two or three
days. Very rarely have they not settled within one or two days. But
taking the maximum period of activity, under conditions where no food
is available at four days, the total distance traveled might be 444 feet.
This is on the basis that they would travel 55.5 inches per hour, and
keep it up continuously for four days. This distance, of course, would
never be approached under actual conditions. Two active young were
liberated on an ordinary picking box, and one crawled eleven inches
and the other six inches in one hour. The temperature was 800 F. This
test was duplicated with a temperature of 96 F., and the longest dis-
tance covered in one hour was eleven inches, and the shortest distance
eight inches. We have not yet succeeded in getting the young red scale
to live more than four days without food. Picking boxes, gloves, ladders;
etc. would therefore be safe to take into a clean grove without fear of
infestation through these things after a period of four or five days, or,
to be surely on the safe side, one week.
BULLETIN 222]
UNIVERSITY OF CALIFORNIA-EXPERIMENT STATION.
Rate of travel over sand and orchard soil. A number of experiments
were made on the rate of travel of the young insects over sand and
orchard soil. Some of these are tabulated below:
Tempera- Number Radius
Date. ture. insects. Kind of soil. of soil. Time. Results.
July 15 .----- -. 90F. 15 Sand 1 inch 4 hrs. 0 crossed
July 15 ------ 90 15 Sand 2 inches 4 hrs. 0 crossed
July 15 ____--.. 90 15 Sand 3 inches 4 hrs. 0 crossed
July 18 -- 88 20 Sand 2j inches 17 hrs. 1 crossed
July 19 --------- 85 20 Orchard-soil 21 inches l 17 hrs. 0 crossed
July 18 -------- ---- 85 20 Orchard-soil 2 inches 5 hrs. 0 crossed
July 18 ------- 85 20 Orchard-soil 2 inches 1 14 hrs. 0 crossed
July 22 ------------ 89 15 Orchard-soil 2 inches 18 hrs. 0 crossed
July 20 ------------ 93 20 Orchard-soil 3 inches 15 hrs. 0 crossed
July 21 -- ------- 82 20 Orchard-soil 3 inches 19 hrs. 2 crossed
July 23 --- 63 10 Orchard-soil 3 inches 19 lrs. 2 crossed
July 24 ---- 78 20 Orchard-soil 3 inches 24 hrs. 2 crossed
July 25 --__----------- 78 25 Orchard-soil 3 inches 24 hrs. 0 crossed
July 25 -- 76 20 Orchard-soil 3 inches 24 hrs. 0 crossed
Nov. 29 -------------- 18 Sand 2j inches 24 brs. 2 crossed
Nov. 29 --_ --------- ----------I 18 Sand 2j inches 24 hrs. 1 crossed
Nov. 26 ........------------- 12 Sand 2 inches 24 hrs. 2 crossed
Nov. 19 -__. --- -- -------- 12 Sand 1 inch 24 hrs. 2 crossed
July 18 ------------- 88 2 Compacted silt 5 Inches 30 min. 2 crossed
July 18 _----------- 88 2 Compacted silt 5 inches 20 min. 2 crossed
From the above experiments it will be seen that the young red scale
makes very little progress over sand or ordinary orchard soil. Out of
the 319 insects tried only fourteen crossed over the strips of soil indi-
cated, which did not exceed three inches in width. None of them suc-
ceeded in crossing even the narrowest strips until the following day. In
the case of the last two tests, where the soil was compacted in an irriga-
tion furrow, they made very good progress, and traveled at the rate of
about ten inches an hour. If, then, there is a fairly good mulch, as is
maintained in California citrus orchards during the summer, there is
little chance of a young red scale ever making its way from one tree to
another by its own powers of locomotion. But during the winter season
when the surface soil is compacted by rains, or through irrigation during
the summer, there may be some possibility of this occurring. In the
case of the mulch the young scales, in attempting to ascend a small
particle of earth, fall back in the attempt and flounder about without
making very much progress.
On account of the limited powers of locomotion of the insects them-
selves, their spread must be accounted for through outside agencies. Of
these, active insects must be the most important. Among the insects
responsible for their spread, those which are to be found crawling about
on the tree where the scales are are most important. Coccinelids are,
therefore, entitled to first consideration. These may be feeding on the
scales themselves, and thus allow abundant opportunity for the young
scales to crawl upon them. Indeed, it has not been uncommon to actually
THE RED OR ORANGE SCALE.
observe many of the beetles carrying young scales on their bodies in the
insectary and also in the field. Others, such as lace wing flies, Dia-
brotica, and ants are likely to aid in the spread of young scale insects.
The wind is hardly as important as popularly believed in aiding the
spread of scales. Of course the adult male may be carried some distance
by the wind, but the active young are too heavy for their size to be
transported very far. They are not easily dislodged from the tree by
the wind, but once dislodged may be carried a short distance while they
are falling, if the wind is sufficiently strong. But the wind is likely to
be more important in distributing infested leaves about. Here, again,
it is the dead leaves that are conveyed most easily, and these are not so
likely to have live scales as the green or yellowed ones.
I rc)%
J ^ / ( Ki -\
'4 ..v C^ -' -
FIG. 20.-Aphelinus diaspidis. 1 Egg. x15. 2 Larva. x65. 3 Head segment
showing mandibles. 4 Pupa. x60.
PARASITES.
Aphelinus diaspidis Howard.
The most common parasite of the red scale at the present time is
Aphelinus diaspidis Howard. Indeed, in the examination of red scales
from many parts
of the citrus belt
during the past
three years this has -
been practically :::-:.- A
the only one met -
with in any num- 7 J -
bers. In the liter- \\
ature that has ap-
peared, and ad-
dresses made in
this state on par-
asites, this particu- Fro. 21.-Aphelinus diaspidis How. Parasite on Red and
Yellow Scales. x39.
BULLETIN 222]
UNIVERSITY OF CALIFORNIA-EXPERIMENT STATION.
lar insect has not been mentioned in connection with the red scale.
It may be possible that it has recently become prominent, or that it was
considered under another name. It is true that the parasites of the red
scale have received less attention than those of some of the other scales.
That it has become abundant rather recently is not impossible. A.
diaspidis was first described by Dr. L. O. Howard in 1880 from speci-
mens bred from Aulacaspis rose from Florida. Specimens from the
same scale were also collected at Santa Barbara, California, about the
same time. It has, therefore, been known from this State for thirty
years. This parasite has also been bred from a species of Mytalispidis
from Japan and from Aspidiotus juglans regia, or the walnut scale.
It has been usual here to speak of such a parasite as this of the red
scale as an internal parasite, but this is not strictly true, for at no stage
of its life cycle is it within the insect. It is true that all of its life,
excepting as an adult, is spent beneath the scale covering, but it is
always outside the insect itself. The egg is deposited outside of the
insect, and upon hatching the larva attaches itself to the body and sucks
out the juices. In the case of the yellow scale parasite Aspidiotiphagus
citrinus, which also attacks the red, it lives within the body of the insect
and is strictly an internal parasite. Coccophagus lecanii and Aphycus
"I,,S,, parasites of the soft brown scale (Coccus hesperidum) are also
strictly internal parasites; that is, they live within the body of the
insect and entirely surrounded by the body tissues from which their
food supply is derived.
ECONOMIC VALUE.
While it is not uncommon to find this parasite on red scale from many
sections of the citrus belt, it has never been seen occurring in large
numbers. Examination and counts have been made at various times
during the past three seasons, and, thus far, we have not found the
number of scales parasitized to exceed 10 per cent. This amount of
parasitization is, of course, of little value in checking the number of
scales. The parasite was usually found most abundant where the scales
were most numerous.
DESCRIPTION OF THE STAGES.
The egg is yellowish white in color, ovate in form, measuring .16 mm.
long and .96 mm. wide. There is a conspicuous micropyle projecting
from the narrower end and also attached to this a short stalk that is
doubled back on itself. The chorion is smooth, with spherical granular
bodies showing through with transmitted light.
The larva when full grown appears as a more or less structureless top-
shaped globule, measuring, when segments are normally extended,
.75 mm. long and .5 mm. wide. It tapers considerably more toward the
THE RED OR ORANGE SCALE.
posterior end, and there is a slight difference between the dorsal and
ventral surfaces. The distance between the upper and lower surfaces is
a little less than the width of the body so that there is some indication
of flatness. The color is glassy white, with the food in the digestive
tract showing distinctly yellow, oval in shape, and measuring about one
half the dimensions of the larva itself. There are thirteen indistinct
segments, not including the button at the tip. The head end is broadly
rounded, with the first segment disc-shaped and firmer than the others,
with the small mouth opening in the center. This mouth opening is
about .20 mm. in diameter, and there are two chitinous spines, man-
dibles, projecting toward its center in front. These spines are .18 mm.
in length and .15 mm. wide at the base where the muscle attachment
occurs. From near the base they suddenly narrow into a sharp pointed
spine which is chitinous at tip and brown in color. These are used for
piercing the outer wall of the scale and for holding it in place while the
fluids are sucked from the body.
The pupa is dark yellow in color, with ocelli and eyes reddish brown,
and a similar pigment extending around the anterior margin, and to a
less extent about the posterior margin of the head. Length .75 mm.,
width .375 mm. The adult appendages, enclosed in their sheaths, lie
close to the body on the ventral side. Always accompanying the pupa
are from six to ten black or dark brown torpedo like bodies .125 mm.
long and .055 mm. broad, which are evacuations from the digestive tract
and are expelled by the larva preliminary to pupation.
The adult. Length .78 mm., wing expanse 1.9 mm., general color
yellow, eyes black, ocelli dark red, antenna dusky and darker at tip.
The eyes are not covered with hairs. The antennae are six jointed, the
club being about three times the length of the penultimate point. The
fringe of the wings is narrow.
LIFE HISTORY AND HABITS.
The duration of the egg stage is from four to five days, of the larval
stage twelve to sixteen days, and of the pupal stage eight to ten days.
The adult, under nearly normal conditions, usually died in four or five
days.
This parasite does not always emerge through an exit hole in the scale,
but very commonly simply pushes its way out from under the scale.
The scale covering seems to be loosened from the surface in most cases
so that this means of emergence is comparatively easy. This is further
brought about by the movement of the parasite, and also because of the
fact that the scale covering is always separated from the insect and has
a chance to loosen before the parasite is mature. In case, however, the
scale covering is held securely to its resting surface the parasite eats out
an irregular hole in the scale covering just beyond the molted skin, in
BULLETIN 222]
UNIVERSITY OF CALIFORNIA-EXPERIMENT STATION.
the case of female scales, and at the posterior third in the case of male
scales. The parasite almost invariably is lying on its back as a pupa.
Not infrequently two pupas are found under one scale, and one case has
been observed where there were three.
The egg is deposited under the scale covering, but either on the upper
or lower side of the insect itself, most commonly on the lower. It is not
inserted within the body of the insect. Preliminary to oviposition a
thorough examination is made of the scale by alternately tapping with
the antenna from the center of the scale to the periphery. Upon reach-
ing the edge of the scale a rapid backward movement is made, at the
same time turning slightly around so that the entire surface is explored
by the antenna in from five to eight backward and forward movements
in a remarkably short time. This procedure may occur with but one
scale before the ovipositor is inserted, and again a dozen or more may
be gone over without finding a suitable scale for oviposition. But the
parasite does not rely alone on the exploration with the antenna, for
the ovipositor may be inserted many times without any eggs being
deposited. Insertion with the ovipositor may occur with the insect
beneath in various conditions, and not infrequently it is dead and
shriveled up. But exploration by the ovipositor is the final reliance for
the placing of the egg.
The ovipositor is not inserted under the scale covering, but through it
just beyond the insect beneath. The parasite is facing away from the
scale during oviposition so that the ovipositor is pushed down and back-
ward toward the center of the scale.
A specific case will serve to illustrate the behavior during oviposition.
Parasite inserted ovipositor and laid egg in scale No. 1 occupying five
minutes. One insertion was made in each of three other scales occupy-
ing from one to three minutes each. No eggs deposited. In scale No. 5
ovipositor inserted eleven times, and remaining in scale as follows:
Smin.; I min.; 1 min.; 1i min.; 1 min.; 1 min.; 1 min.; 1 min.; J min.;
1i min.; 61 min. Scale lifted and but one egg deposited, this undoubt-
edly at last insertion.
Eggs may be deposited under scales of various stages as follows:
Female between first and second molt and between second molt and egg
laying. Male after first molt, propupa and pupa. In no case has a
larva of the parasite been seen with a scale during the molting periods
or during the egg-laying period. The scale during these periods is very
different than at other times. The body wall is hard and glassy, while
the contents are more fluid and the insect adheres firmly to the scale
covering. Between the molts the body wall is flexible, is not so distended
by the body fluids, and the scale covering very readily separates from
the insect itself. This last point accounts for the readiness with which
the covering is lifted in many cases to allow the escape of the parasite.
THE RED OR ORANGE SCALE.
The fact that the parasite has not been seen infesting a scale during
the molting periods or the egg-laying stage is accounted for because of
the checking in growth of the scale. So far as our observations have
gone, eggs are not deposited under scales in these conditions. The effect
of the parasite on the host seems to be the only explanation for the fact
that molting may not occur later, and before the parasite has developed.
The feeding of the parasite larva seems to check the development of
the scale as soon as it is attacked, or soon thereafter.
Some of the Chalcid parasites have been recorded as feeding at the
puncture holes made by the ovipositor.' This has not been observed in
the case of A. diaspidis. Several hundred insertions of the ovipositor
have been watched during the past two or three years, so that such a
habit can not be, at least, counted common. The egg parasites mentioned
in the article cited would be able to get the drop of the contents which
would almost certainly be exuded. But we are not so sure that any
liquid would be exuded in the case of a puncture in the scale covering of
some of the armored scales.
This would be possible during the molting periods, or the egg-laying
period, when the body is well distended and intimately associated with
the scale covering. But A. diaspidis has not been seen to oviposit under
such scales. And at other times, while the ovipositor is inserted through
the scale covering, it does not puncture the insect itself, or if it does, the
liquid would be apt to exude underneath the covering and not neces-
sarily through the puncture hole. Such a habit would be more likely to
occur with those parasites that deposit their eggs within the body of the
host, instead of externally as diaspidis.
Observations have been made on this species feeding on a droplet of
honey dew and also some indication that they feed on plant tissue. They
have been observed many times lying prone upon the surface of the
fruit or leaf working the mandibles and going through all the move-
ments of feeding. But no feeding scars have been seen with the lower
power lenses. Coccophagus lecanii has this habit, and leaves very dis-
tinct feeding scars. It also strokes the soft brown scales to secure the
drops of honeydew similar to the ants. No males of A. diaspidis have
yet been seen, although a large number of specimens have been collected
from various places. Parthenogenetic reproduction, therefore, must be
the usual way. An isolated female that had emerged was immediately
placed in a glass vial, and an hour or two later deposited an egg beneath
a scale and which later hatched.
'Howard. Jour. Ec. Entomology. Vol. 3, No. 3.
BULLETIN 222]
UNIVERSITY OF CALIFORNIA-EXPERIMENT STATION.
Other species of Hymenopterous parasites reared from the red and
yellow scales in California are:
Prospaltella aurantii Howard.
Coccophagus lunulatus Howard.
Aspidiotiphagus citrinus Craw.
Signiphora occidentalis Howard.
Aphycus immaculatus Howard.
Alaptus criococci Girault.
Physcus flaviventris How., has been reared from Chrysomphalus
aurantii Mask. from Manila, P. I.
KEY TO THE SPECIES OF PARASITES RECORDED FROM Ohyrsomphalus aurantii AND
THE VARIETY citrintU.
Antennce 6-jointed.
Wings with short fringe, Aphelinus diaspidis.
Wings with long fringe, Signiphora occidentalis.
Antennae 7-jointed.
Physcus flaviventris.
Antennw 8-jointed.
Stigmal vein lacking; fringe long, Aspidiotiphagus citrinus.
Stigmal vein present; fringe short.
Marginal vein as long or longer than submarginal, Coccophagus lunulatus.
Marginal vein much shorter than submarginal, Prospaltella aurantii.
Antenn; 9-jointed.
Aphycus immaculatus.
Antennw of female 8-jointed, of male 10-jointed.
Alaptus eriococci.
Prospaltella aurantii Howard.
This species was originally described by Dr. Howard in Insect Life,
Vol. VI, p. 231, in 1894. The specimens were reared by D. W. Coquillett
p`~
/ V
FIG. 22.-Prospaltella aurantii How.
After Howard.
is only occasionally met with.
ancylus, A. pini, A. juglans
Eulecanium persicce, Chionaspis
x50.
It is
regia,
sp.2
from Chrysomphalus aurantii
var. citrinus from San Gabriel,
California, in 1887. The origi-
nal generic name was given as
Coccophagus, and later as Pros-
palta, but the latter was pre-
occupied so that the genus as it
now stands is Prospaltella.1
This parasite is not common
on the red or yellow scales, and
also recorded from Aspidiotus
Lepidosaphes beckii, L. alba,
Coccophagus lunulatus How.
This parasite was described from one female reared from Chrysom-
phalus aurantii from Los Angeles in 1892. Red scale infested leaves
'Howard. Jour. Ec. Ent. Vol. 4, No. 1, 1911.
'Howard. Tech. Series I, Bull. U. S. D. A., Bur. Ent., 1895.
'Howard. Insect Life. Vol. VI, p. 232.
THE RED OR ORANGE SCALE.
were placed in a jar and a week later the above parasite issued.3 There
is some doubt in the writer's mind about this insect being reared from
the red scale. Species of the genus Coccophagus, with this single excep-
tion, do not attack members of the Diaspince group. The size of the
//.---
N
FIG. 23.-Coccophagus lunulatus How. x50. After Howard.
parasite is also rather large to mature in a red scale. The size as given
in the original description is .93 mm., while the average dimensions of
the mature scale are .78 mm. wide and 1 mm. long. The lengths of the
other parasites of this same host are .61 mm., .55 mm., .53 mm., .58 mm.,
and .70 mm. It would not be unlikely that it issued from Coccus hes-
peridum, which are so frequently found on the orange leaves.
Aspidiotiphagus citrinus Craw.
A discussion of this insect will be found under the head of "Yellow
Scale Parasites."
Signiphora occidentalis How.
This insect was described
by Dr. Howard from mate- d
rial reared from Chrysom-
phalus aurantii var. cit- = 7:.---.
rinus, from San Gabriel,
California. It has also
been taken from Lepido- ,
sophes gloverii, Aspidiotus
cydonim and Aleyrodes sp.
The original description
is given in Insect Life, FIG. 24.-Signiphora occidentalis How. x50.
Vol. VI, p. 235. After Howard.
BULLETIN 222]
UNIVERSITY OF CALIFORNIA-EXPERIMENT STATION.
Aphycus immaculatus How.
This species has been reared by D. W. Coquillett from Chrysomphalus
aurantii from Los Angeles, California, and described by Dr. L. O.
Howard in Insect Life, Vol. VI, p. 236. It has not been observed by us
during the past three years.
FIG. 25.-Aphycus immaculatus How. x50.
After Howard.
Alaptus eriococci Girault.
This species has been reared from Chrysomphalus aurantii and Rhi-
zoccus araucarice from Los Angeles, and described by Mr. A. A. Girault
in the Annals of the Ent. Soc. of America, Vol. I, No. 3, 1908.
Rhizobius Jopantht. Blaisd.
This Coccinelid is probably the commonest and most abundant one
feeding upon the red scale. While it is not restricted in its feeding to
this scale exclusively it has been found more often associated with it
4-
v,- -' H
than any of t.-heus other sp. Larva, pupa, adult. Reared from Aspple. It has been called
the "Purple Scale Rhizobius,EDA" but this name is no more justifiable than
Rhizobius lopanthce. Blaisd.
This Coccinelid is probably the commonest and most abundant one
feeding upon the red scale. While it is not restricted in its feeding to
this scale exclusively it has been found more often associated with it
than any of the other scales, unless it be the purple. It has been called
the ''Purple Scale Rhizobius,'' but this name is no more justifiable than
THE RED OR ORANGE SCALE.
"Red Scale Rhizobius." In fact, the latter would be an appropriate
common name just as the "Black Scale Rhizobius" would be similarly
appropriate for Rhizobius ventralis. Where both the red and black
scales occur in the same orchard, or even on the same tree, ventralis will
be found with the black and lophanthce with the red.
A I
FIG. 27.-Prospaltella sp. Internal parasite from
Aspidiotus hederae Vail.
The eggs of R. lophanthce are often found beneath the red scale.
Usually but one or two are found under the same scale. They are small
oval shaped eggs white in color with a metallic iridescence. Upon
watching the larva makes its way from beneath the scale, consuming first
the scale under which it is found, if it offers suitable food, and later
attacks many different scales before reaching maturity. It eats out an
irregular hole, rectangular usually, in the scale covering and most com-
monly just beyond the insect which is lying beneath.
FIG. 28.-Rhizobius lopanthae Blaisd. Larva
and pupa, xl0; and adult, x5.
The mature larva is 4 mm. in length and about 1 mm. wide. The
general color is dark gray with a lighter rectangular area on dorsal line
of first four abdominal segments. There is also a strip similar in color
on either side of the dorsal line on the meso- and meta-thoracie segments,
also two narrower strips more laterally on last four abdominal segments.
BULLETIN 222]
UNIVERSITY OF CALIFORNIA-EXPERIMENT STATION.
There is a double row of conspicuous papillve from each of which arise
two or three hairs, the central papilla and hairs being longest. The
hairs are light colored. There is a row of very small inconspicuous
hairs, two on each segment, on either side of the dorsal line.
The adult is a small beetle, measuring 2 to 21 mm. in length. The
elytra are metallic black in color and covered with grayish or light
brown hairs. The pro-thorax is brown with a faint darker band extend-
ing horizontally across the middle. Eyes black. Ventral surface and
legs brown. This is sometimes called the "little brown neck beetle"
.
1 2 3
4 5
If \
FIG. 29.-Some common ladybird beetles that feed on the Red Scale. x5.
1. Scymnus marginicollis, Mann.
2. Rhlzoblus lophanthae, Blalsd.
3. Scymnus nebulosis, Lee.
4. Hippodamia convergens, Guer.
5. Coccinella californica, Mann.
6. Hippodamia ambigua, Lec.
7. Hippodamia ambigua, Lec.
THE RED OR ORANGE SCALE.
because of the color of its pro-thorax, but others nearly similar in size
and appearance might be confused with it.
Besides the red scale, this beetle is known to attack the yellow
(C. aurantii var. citrinus) the oleander (Aspidiotus hederce) the greedy
(A. rapax) and the purple (L. beckii). It has been found commonly
feeding on the purple scale, both in the vicinity of Los Angeles and San
Diego. Its attacks on the purple appear to be limited more to the
young or partly grown. The mature purple with its firm covering seems
to be better protected from its attacks.
THE STEEL-BLUE LADYBIRD BEETLE.
Orchus chalybeus. Boisd.
This beetle is most abundant in Santa Barbara County. It is found
well distributed over the citrus section of that county, and often occurs
in large numbers. It is said to feed especially on the red and yellow
scales. But it is not limited to those scales, and where it was seen most
abundantly in Santa Barbara County it was associated with the black
scale.
OTHER ENEMIES.
There are many other Coccinellids which may feed on the red scale
occasionally, but these are still more general in their feeding than the
two mentioned. Our commonest native species including Hippodamia
convergens, Coccinella californica, Chilocorus bivulnerus, and others are
all very general feeders and no one of them is particularly effective as
a check on the scale. Aside from the Coccinellidce, other enemies are
certain species of the families Chrysopidce, Hemerobiidce, and Reduviide,
and the predaceous mites.
THE YELLOW SCALE.
(Chrysomphalus aurantii var. citrinus Coq.)
This scale is very similar to the red (C. aurantii), and is classified as
a variety having the varietal name citrinus. It is widely distributed
over the citrus belt of southern California, often associated more or less
with aurantii. But in addition to its occurrence in the southern part of
the state it is also found on the citrus trees of the Sacramento Valley.
There it is the most important scale occurring on citrus trees. In the
same section the typical aurantii is not known. Why it doesn't occur
there is not satisfactorily accounted for. In the interchange of nursery
stock aurantii has probably had abundant opportunity of becoming
established in the section. In fact, it is more likely to have been intro-
duced, because of its wider occurrence in the south than citrinus. But
it is not altogether improbable that the variety has predominated and
become established. Experiments are now under way with a view to
determining the factors responsible for such a distribution.
BULLETIN 222]
UNIVERSITY OF CALIFORNIA-EXPERIMENT STATION.
In the citrus belt of the south the yellow occurs in various degrees of
severity ranging from occasional scales scattered about on parts of the
tree, to badly infested trees requiring treatment. In Santa Barbara
County at the present time the yellow is more common than the red. In
San Bernardino and Riverside counties the yellow ranks second in
importance among the insects of citrus trees, the red holding first place.
In Los Angeles, Orange and San Diego counties the yellow is not
counted among the first three. In these counties, to be sure, its place
may be pre-empted by the purple. In former years it is said to have
occurred in great abundance in certain sections as San Gabriel in Los
Angeles County.
FIG. 30.-Yellow Scale, chrysomphalus aurantii var. citrinus,
on orange.
Economic importance. While the yellow scale may frequently become
abundant to the extent of injuring the tree, it can not be counted as
serious as the red. This is partly because of its well known habit of
avoiding the twigs and branches, and infesting largely the fruit and
foliage. The yellow is found on the branches to some extent, but usually
only in severe infestations, and even then only scattering. Trees have
been seen where the leaves and fruit were completely covered with yellow
scale for two or three years in succession, yet the tree itself was not
seriously damaged. Of course, with such an infestation the tree is
injured because of the injury to the leaves, and the fruit is rendered
unfit for market. But, if a similar infestation had occurred with the
red, a large portion of the tree would have been killed outright.
Another point that makes the yellow less to be feared in many sec-
THE RED OR ORANGE SCALE.
FIG. 31.-Yellow Scale on orange leaf; upper surface.
FIG. 32.-Yellow Scale on under side of same leaf as
shown in Fig. 33.
4--I'L. 222
BULLETIN 2221
UNIVERSITY OF CALIFORNIA-EXPERIMENT STATION.
tions is its apparent lack of vigor, either of breeding or of becoming
established rapidly. Exceptions may occur to this statement, as they
do in the north and also in cases in the south. But it is not uncommon
to find scattering infestations of yellow in a grove for years without
becoming abundant enough to attract attention or make it worth while
inaugurating control measures. Here is the opportune point to give
credit to the parasites. But in those cases under consideration there
were less parasites than on the red, and this maximum was only 10 per
cent.
Differences between the red and yellow scales. Structurally there are
no differences, thus far discovered in the insect itself, between the
species auranlii and its variety cit-
rinus. Exactly the same morpholog-
ical characters occur in both, so that
under the microscope it is not possible
to be sure whether it is the red or yel-
low that is being examined. But the
difference in appearance as they are
found on the tree is usually not diffi-
cult to determine. The yellow is much
lighter in color, is often less convex
and often appears slightly larger in
diameter. The additional fact that
they are not found to any extent on
the twigs, makes the field determina-
tion easy enough. But if only a few
specimens are seen on a leaf, and these
FIG. 33.-Yellow Scale showing exit are not typically red or yellow, the
hole of Aspidiotiphagus citrinus.
Mouth parts of scale showing determination is difficult and often
below in opening, xl00. impossible. This is particularly true
of old, dead scales which in the case of the yellow become much darker in
color and makes the similarity more complete.
The difference in color is not due to the insect itself so much as in
the scale covering. When the insects are free from the scale covering.
as between the molts, it is often very difficult to distinguish the red from
the yellow, though before the same scales were lifted, the difference may
have been evident enough. But during the molting periods the red is
much darker in color than the yellow. Since the dorsal half of the
cast skin is incorporated into the scale this difference persists in the
scale covering. The color of the insects is most usually a light yellow,
both with the red and yellow. But there is considerable variation, and
the red is often apt to be distinctly darker in color, this being most
marked, as intimated during the molting period or during the produc-
tion of young.
THE RED OR ORANGE SCALE.
Aside from the difference in habits of the two scales in attacking the
twigs, there are other differences in habits. Where there are but a few
scattering scales the yellow will be most likely to occur on the lower
side of the leaves and usually too on those leaves near the lower part of
the tree. In severe infestations also the lower side of the leaves are
likely to have the greatest number of scales. Of course the red will
often be found on the under side of the leaves as well as the upper, but
the habit the yellow has sometimes of settling entirely on the lower side
is not so true. The red is not averse to getting into the light and more
open parts of the tree, while in many cases the yellow has the opposite
habit. Where the occurrence of the yellow is severe, all parts of the tree
may be attacked. But it can not be said that the yellow doesn't like
heat, for it is most important in the warmest part of the southern citrus
belt, and occurs exclusively in the large interior valleys of the north,
where the summers are hotter than any part of the southern belt.
The life history of the yellow has been found to agree in all essential
particulars with that of the red. The discussion of the seasonal history,
locomotion, and spread also corresponds in both, so that these topics
will not be again considered.
PARASITES.
Aspidiotiphagus citrinus Craw.
While the same parasite is likely to attack either the red or yellow, it
being unlikely that it is able to distinguish the varietal differences, yet
our acquaintance thus far with the following parasite has been largely
in connection with the yellow. C .-.
This is Aspidiotiphagus cit- 1
rinus Craw, formerly known
in this state as the "golden .
chalcid." It has been met 's.
with most commonly in Santa .' ---.
Barbara County. That it oc-
curs here on the yellow may
be accounted for because of
the fact that the yellow is the
commonest of the two scales 4 -- '
in that county. However,
some red were obtained in one
of the localities where the yel- 3
low occurred, but we did not
FIG. 34.-Aspidiotiphagus citrinus. 1 Egg. x175.
happen to secure any of the 2 Larva. x30. 3 Yellow Scale harboring
parasites from this material. larva. 4 Pupa. x65.
This parasite was only rarely obtained during the past three years from
either red or yellow scale material obtained from about Whittier, Los
BULLETIN 222]
UNIVERSITY OF CALIFORNIA-EXPERIMENT STATION.
Angeles, Pomona, Redlands, Riverside, Santa Ana, and San Diego. It
was found more abundantly at Marysville, Oroville, Chico, Sacramento
and Santa Barbara. Indeed, in the Sacramento Valley section is where
the heaviest parasitization has been noted. Counts oil a large number
of scales from that section showed the percentage of parasitization to
run as high as 67.
Aspidiotiphagus citrinus has been taken rather abundantly from
purple scale in certain sections, especially where fumigation has not been
regularly practiced. It, therefore, attacks the purple scale readily, and
is not limited solely to the yellow as is supposed by some.
The egg of A. citrinus is oval in general shape, but distinctly flattened
on one side. There is a minute stalk at one end and the egg is slightly
more tapering at this end; color transparent, granular; length .08 mm.,
width .007 mm. The egg is found within the body of the scale. The one
described was deposited at 5 P. M. December 30, 1910, and was dissected
from the scale and examined on January 3, 1911.
The mature larva is glassy white in color; length .85 mm. long and
.35 mm. broad at widest part, which is about the middle. It is thus much
more elongate than that of
diaspidis. The segments are
very indistinct. While the
middle is slightly widest, the
head end is broad, but there -
is a gradual tapering to a c
narrow point at theposterior
end. The mouth opening is
in the center of the disc-
shaped anterior se gmen t.
The mandibles are much nar-
rower at the base than those FIG. 35.-Aspidiotiphagus citrinus Craw. x40.
Parasite of Yellow and Red Scales.
of diaspidis. This character,
together with the difference in the general shape, will readily distin-
guish the two larva. The larva of Aspidiotiphagus citri is lives
strictly within the body of the insect itself.
Thi pupa. Length .6 mm., width .28 mm. The general color upon
first changing from the larva is white or whitish yellow, but it later
turns very much darker. The head is light gray and thorax and abdo-
men almost black, with the abdominal segments lighter in color at the
margins, giving a horizontal striped effect. The eyes and ocelli are red
or reddish brown.
Thec adult. General color yellowish black. Head dull yellow, ocelli
red, eyes black. Thorax dark yellow, with darker areas about bases of
wings. Abdomen black, lighter at tip. Legs pale colored. Antenna'
THE RED OR ORANGE SCALE.
^a~
FIG. 36.-Fruit showing cells for rearing parasites.
.~LL~f
FIG. 37.-Above, cages enclosing small orange trees for
studying parasites. Below, method of keeping accu-
rate records on life history of scales.
BULLETIN 222]
UNIVERSITY OF CALIFORNIA-EXPERIMENT STATION.
8-jointed, comparative lengths as follows: 5, 25, 10, 8, 7, 10. 13. 18.
Wings narrow, with a very long fringe; basal half dusky.
Life history work carried on with this parasite during the winter
months indicates that 67 or 68 days are necessary for the complete life
cycle. Adults placed in cells on fruit infested with scale were seen to
oviposit in the scales on January 6th, and four adults issued on March
14th and 15th. This period being the coldest and wettest of the season
must account for the slow development. During September the life
cycle has been determined to occur in thirty days. The scales attacked,
whether they be yellow or purple, are, with a few exceptions, always
in the second stage, that is between the first and second molts.
SYSTEMATIC POSITION OF CHRYSOMPHALUS AURANTII MASK.
The family Coccidc, which includes the scale insects, is divided into
six sub-families. The red scale belongs to the sub-family Diaspilnae,
which includes all those scales having flattened chitinous lobes at the
posterior end of the body forming the pygidium. The genus Chrysom-
phalus is distinguished by having three distinct pairs of these lobes.
There are in California but three species and one variety coming within
this genus. The species aonidium is separated from the others by having
four groups of spinnerets. The others have no groups of spinnerets. In
the species tenebricosus the plates are scarcely branched, while in the
species aurantii and the variety citriinus the plates are strongly
branched.
C. aonidum, formerly known as ficus, is known as the Florida red
scale. It is not, however, as serious a pest there as our red scale here.
It is especially likely to infest plants in conservatories or under glass.
Its occurrence in this state is based on an infestation of palms in a
greenhouse.
THE RED OR ORANGE SCALE.
BIBLIOGRAPHY.
For the bibliography of Chrysomphalus aurantii up to 1903, the
reader is referred to Mrs. Fernald's "Coccidse of the World." The
following is the bibliography since 1903, which has been kindly fur-
nished by Mr. E. R. Saccer of the Bureau of Entomology, Washington:
Chrysomphalus aurantii Mask.
Ehrhorn. E. M.: 1st Bien. Rept. Comm. of Hort. Sta. Cal. 1903-04. pp. 112-113.
Sanders: Proc. Ohio Ac. Sci., iv (2). Sp. papers 8, p. 71 (1004). Figs. 15-1(.
Gives bibliography and description.
Hempel: Bol. Agr. Sao Paulo, V, p. 322 (1904).
Describes hosts, etc.
Trabut, Dr.: Bull. Agr. de Alg. et del Tunisie, X, No. 23, p. 521 (1904).
"Au sujet d'un insecte destructeur de 1'oranges."
Theobald: 2d Rep. Ec. Ent. Br. Mus, p. 187 (1904).
Record of Ys only.
Kirkaldy, G. W.: The Entomologist, Vol. XXXVII, Sept. 1904, p. 228.
Cockerell, T. D. A.: Proc. Davenport Acad. of Sciences Vol. X, p. 134. 1905.
Dickel, Dr. O.: Zeit. f. wiss. Inskt Heft II Bard I, Nov. 20, 1905. p. 447.
Dewar. W. R.: 1st Ann. Rep. Gor. Entom., Orange River Colony (1905), p. 36.
"This is at present the greatest insect enemy of citrus trees in the O. R. C."
Orange River Colony.
Leonardi, G.: Redia, iii, p. 1 (1906). Fig.
Described as Aonidiella taxus, but appears to be a synonym of A. aurantii.
Newstead, R.: The Inst. of Commercial Research in the Tropics. Liverpool Univ.
Quarterly Jn. Vol. 1, No. 11, April, 1906, p. 69.
Frequently received from Egypt.
Craw, A.: Rep. Dic. Entom., Hawaii Bd. Ag. & Forestry, Dec. 31. '06, pp. 143, 152.
"Well established in the islands."
Ierrera, A. L.: Bol. d. 1. Com. de Parasitologia Agricola Tomo III, Num. I (1906).
Ehrhorn, E. M.: 2d Bienl. Rep. Com. of Hort. Sta. of Cal., 1905-'06. pp. 23, 25.
and 224.
Green. E. E.: Trans. Linn. Soc. of London, Vol. XII, pt. 2. Dec. 1907, p. 203.
Recorded from Mauritius, Ceylon, India, S. Europe, Syria, Natal, Cape Colony,
China, Japan, Australia, New Zealand, Java, New Caledonia, Samoa, Fiji,
Hawaiian Islands, W. I., U. S. A.
Kuwana, S. I.: Bull. Imp. Cent. Agr. Exp. Sta., Japan, Oct. 1907, p. 196.
Bibliography on Podocarpus chinensis, Acacia, orange and tea plants.
Carnes, E. K.: 2d Bien. Rep. Com. Hort. Sta. Cal. 1905-06 (1907), pp. 214-216.
Leonardi, G.: Estratto dal Boll. del Lab. di Zool. general e agraria della R. Scuola
Sup. d'Agric. di Portici, 24 Mar. 1907.
Europe (Greece, Turkey, Italy, Spain), Syria, Natal, Good Hope, Is. Maurizio
e Ceylon, China, Japan, Australia, New Zealand, Samoa, Is. Fiji, Hawaii, West
Indies (N. Y., Fla., Ohio, Cal.). Gives 15 figures and list of food plants.
Fuller. C.: The Natal Ag. Jn. & Mining Record, vol. X, No. 9, Sept. 27, '07, p. 1036.
The parasitic fungus Sphaerostilte coccophila is effective on the coast.
Lindinger. L.: Der Pflanze Ratg. fur Tropical Landwirthschaft No. 23. Dec. 21, '07.
Jahr III, p. 359.
Draper, W.: Notes on the Injurious Scale Insects and Mealy Bugs of Egypt (Cairo).
1907. p. 8.
Common throughout Egypt.
Newman. L.. .: Jn. Dep. Ag. of Western Australia, Vol. XV. pt. 12. Dec. '07, p. 915.
"This is beyond question the most serious scale pest of the citrus trees in this
state, and also of many other garden plants."
Ehrhorn. E. M.: 2d Bien. Rep. Com. of Hort. Sta. of Cal. 1905-'06, p. 23.
Lea, A.: Insect and Fungus Pests of Orchard and Farm (3d edition), Tasmania,
p. 64 (1908).
BULLETIN 222]
10U UNIVERSITY OF CALIFORNIA-EXPERIMENT STATION.
Froggatt, W. W.: The Ag. Gaz. of N. S. W., Sept. 1908, vol. XIX. part !1. p. 7;4.
"Common all over Cyprus gardens," on roses and wattles.
Froggatt, W. W.: The Jn. Dept. Ag. of So. Austr., Feb. 1909, vol. XII. No. 7.
Ip. 20.
Cook. A. J.: Off. Rep. 34th Fruit-Grow. Con. of Cal., p. 50, Sacramento (190Si.
Leonardi, G. : Cherm. Ital. Fasc. IV, Portici. 1908.
Newman, L. J.: Jn. Dept. of Ag. W. Australia, Dec. 1908, vol. XVII. p. 942.
Day. C. A.: Proc. of 33d Fruit-Grow. Con. of Cal.. p. 163. Sacramento ( 1fS i.
Ehrhorn, E. M.: Proc. of 33d Fruit-Grow. Con. of Cal., pp. 147-159, Sacramento
(19)0S).
(ook. A. ..: Pomona Jn. of Ent., vol. I. No. 1, March, 1909, pp. 14-21. figs. 11-15.
Severin, II. C. and H. II. P.: Jn. Econ. Entom., vol. II, No. 4, p. 29.Au. 1909.
luwana, S. I. : Jn. N. Y. Ent. Soc. XVII, 4, p. 100 (Dec. 1909).
On Ligustrum japonicum, Artocarpus integrifolia. Bonin Island, Jalp:n.
Carnes. E. K.: 3d Bien. Rept. Com. Iort. Cal., p. 25 (1909).
Dean, Geo. A.: Trans. Kans. Acad. of Sciences, XXII. p. 274 (19091.
Lefroy, H. Maxwell: Indian Insect Life, p. 761 (1909).
Lefroy, H. Maxwell: Indian Insect Life, p. 756 (1909).
Brick. C.: Sta. fur Pflanzenschutz zu Hamburg. X, p. 9 (1909.
Only locality and food plants given.
Brick, C.: Sta. fur Pflanzenschutz zu Hamburg. X, p. 10 (1909).
"Auf Cycas circinalis aus Sanisbar, auf Palme aus Java auf Orchid~r aue
Singapore."
Brick, C. Sta. fur Pflanzenschutz zu Hamburg. XI, p. 5 (1909).
STATION PUBLICATIONS AVAILABLE FOR DISTRIBUTION.
REPORTS.
Report of the Viticultural Work during the seasons 1887-93, with data regard-
ing the Vintages of 1894-95.
Resistant Vines, their Selection, Adaptation, and Grafting. Appendix to Viti-
cultural Report for 1896.
Report of the Agricultural Experiment Station for 1898-1901.
Report of the Agricultural Experiment Station for 1901-03.
Twenty-second Report of the Agricultural Experiment Station for 1903-04.
BULLETINS.
Reprint. Endurance of Drought in Soils of
the Arid Region.
No. 128. Nature, Value, and Utilization of
Alkali Lands, and Tolerance of
Alkali. (Revised and Reprint,
1905.)
133. Tolerance of Alkali by Various
Cultures.
147. Culture Work of the Sub-stations.
149. California Sugar Industry.
151. Arsenical Insecticides.
152. Fumigation Dosage.
153. Spraying with Distillates.
159. Contribution to the Study of
Fermentation.
162. Commercial Fertilizers. (Dec. 1,
1904.)
165. Asparagus and Asparagus Rust
in California.
167. Manufacture of Dry Wines in
Hot Countries.
168. Observations on Some Vine Dis-
eases in Sonoma County.
169. Tolerance of the Sugar Beet for
Alkali.
170. Studies in Grasshopper Control.
171. Commercial Fertilizers. (June
30, 1905.)
172. Further Experience in Asparagus
Rust Control.
174. A New Wine-cooling Machine.
176. Sugar Beets in the San Joaquin
Valley.
177. A New Method of Making Dry
Red Wine.
178. Mosquito Control.
179. Commercial Fertilizers. (June,
1906.)
180. Resistant Vineyards.
181. The Selection of Seed-Wheat.
182. Analysis of Paris Green and
Lead Arsenic. Proposed In-
secticide Law.
183. The California Tussock-moth.
184. Report of the Plant Pathologist
to July 1, 1906.
185. Report of Progress in Cereal
Investigations.
186. The Oldium of the Vine.
187. Commercial Fertilizers. (Janu-
ary, 1907.)
188. Lining of Ditches and Reservoirs
to preventt Seepage and Losses.
5-BUL 222
No. 189. Commercial Fertilizers. (June,
1907.)
190. The Brown Rot of the Lemon.
191. California Peach Blight.
192. Insects Injurious to the Vine in
California.
193. The Best Wine Grapes for Cali-
fornia; Pruning Young Vines;
Pruning the Sultanina.
194. Commercial Fertilizers. (Dec.,
1907.)
195. The California Grape Root-worm.
197. Grape Culture in California; Im-
proved Methods of Wine-mak-
ing; Yeast from California
Grapes.
198. The Grape Leaf-Hopper.
199. Bovine Tuberculosis.
200. Gum Diseases of Citrus Trees in
California.
201. Commercial Fertilizers. (June,
1908.)
202. Commercial Fertilizers. (Decem-
ber, 1908.)
203. Report of the Plant Pathologist
to July 1, 1909.
204. The Dairy Cow's Record and the
Stable.
205. Commercial Fertilizers. (Decem-
ber, 1909.)
206. Commercial Fertilizers. (June,
1910.)
207. The Control of the Argentine Ant.
208. The Late Blight of Celery.
209. The Cream Supply.
210. Imperial Valley Settlers' Crop
Manual.
211. How to Increase the Yield of
Wheat in California.
212. California White Wheats.
213. The Principles of Wine-Making.
214. Citrus Fruit Insects.
215. The House Fly in its Relation to
Public Health.
216. A Progress Report upon Soil and
Climatic Factors Influencing
the Composition of Wheat.
217. Honey Plants of California.
218. California Plant Diseases.
219. Report of Live Stock Conditions
in Imperial County, California.
220. Fumigation Studies No. 5; Dos-
age Tables.
CIRCULARS.
No. 1. Texas Fever.
5. Contagious Abortion in Cows.
7. Remedies for Insects.
9. Asparagus Rust.
11. Fumigation Practice.
12. Silk Culture.
15. Recent Problems in Agriculture.
What a University Farm is For.
19. Disinfection of Stables.
29. Preliminary Announcement Con-
cerning Instruction in Practical
Agriculture upon the University
Farm, Davis, Cal.
30. White Fly in California.
32. White Fly Eradication.
33. Packing Prunes in Cans. Cane
Sugar vs. Beet Sugar.
36. Analyses of Fertilizers for Con-
sumers.
39. Instruction in Practical Agricul-
ture at the University Farm.
46. Suggestions for Garden Work in
California Schools.
48. Butter Scoring Contest, 1909.
49. Insecticides.
50. Fumigation Scheduling.
No. 52. Information for Students Concern-
ing the College of Agriculture.
54. Some Creamery Problems and
Tests.
55. Farmers' Institutes and Univer-
sity Extension in Agriculture.
58. Experiments with Plants and Soils
in Laboratory, Garden, and Field.
59. Tree Growing in the Public
Schools.
60. Butter Scoring Contest, 1910.
61. University Farm School.
62. The School Garden in the Course
of Study.
63. How to Make an Observation
Hive.
64. Announcement of Farmers' Short
Courses for 1911.
65. The California Insecticide Law.
66. Insecticides and Insect Control.
67. Development of Secondary School
Agriculture in California.
68. The Prevention of Hog Cholera.
69. The Extermination of Morning-
glory.
70. Observations on Status of Corn-
growing in California.
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