Florida Entomologist
Official Organ of the Florida Entomological Society

VOL. V FALL NUMBER No. 2
OCTOBER, 1921

A HOST PLANT LIST OF APHIDS IN THE VICINITY OF
THE UNIVERSITY OF FLORIDA :
By ARTHUR C. MASON
Our present literature on the insect life of Florida contains
very few references to aphids. In fact, only a few species which
are of economic importance are even mentioned, and nothing
like a list of those occurring in the State has been attempted.
While this paper does not contain a complete list of the plant
lice of Florida or even this section of the State, still it may serve
as a start toward such a list, and may be added to from time
to time.
Previous references include Aphis brassica on cabbage (31)
(32), Myzus persicae on peach and tomatoes (26) (36), Me-
goura solani on tomatoes (35) (36), Aphis gossypii on cotton,
cucurbits, and orange (2) (22) (31) (32), Siphonophora cucur-
bitae on egg-plant (32), Aphis maidis on corn (1), and Tox-
optera graminum on oats (37). These are dealt with purely
from an economic standpoint.
Lists of aphids have been written by several entomologists
for various sections of the country, but none of them cover
Florida. While-it is true that a large number of plant lice are
widely distributed and found in practically all the states, some
others may be restricted to this part of the country alone. There-
fore, a complete list for this State should be prepared.
The insects listed were collected over a period of two years
1 Taken from thesis entitled "Systematic and Biological Studies of Some Florida
Aphididae," presented by the writer to the University of Florida in 1915 for the
degree of Master of Science.
This paper constitutes Part I exclusive of sections on methods of collecting,
mounting, etc. Parts II and III together with references cited will appear in later
issues.
We recommend the goods advertised in The Florida Ento-
mologist. Please mention Entomologist when you write our
advertisers.
"I- "Little Gateways to Science," advertised on back, should be
in every home.

THE FLORIDA ENTOMOLOGIST

(1913-1915) and during all seasons. They represent those found
on both cultivated crops and wild plants. The former, of course,
are brought to the attention of economic workers much more
often because of their importance to agriculture and also their
greater abundance. The list represents about 30 species of
aphids. Many others collected could not be determined because
of lack of mature specimens or winged forms. Undoubtedly
there are in the state many undescribed species of plant lice
and at least two of these were found.
Permanent mounts were made of all specimens and are in the
author's collection. Natural colors cannot be retained in mount-
ed slides and color notes must be made from the live specimens.
HOST PLANT LIST OF APHIDS
Ampelopsis quinquefolia (Virginia creeper)
Aphis folsomii Davis
Andropogon sorghum var. (sorghum)
Sipha flava Forbes.
Apple-see Pyrus malus
Avena sativa (oats) Aphis avena Fitch
Macrosiphum granaria Buckt.
Myzus persicae Sulz.
Toxoptera graminum iond.
Bean-see Phaesolus vulgaris
Beet-see Beta vulgaris
Beta vulgaris (beet) Myzus persicae Sulz.
Brassica oleraceae (cabbage) Aphis brassicae L.
Aphis pseudobrassicae Paddock
Myzus persicae Sulz.
Brassica oleraceae var. acephala (collards)
Aphis p'seudobrassicae
Myzus persicae Sulz.
Brassica oleraceae var. acephala (kale)
Myzus persicae Sulz.
Brassica oleraceae var. botrytis (cauliflower)
Myzus persicae Sulz.
B. oleraceae var. caulo-rapa (kohl rabi)
Myzus persicae Sulz.
Brassica rapa (turnip) Myzus persicae Sulz.
Cabbage-see Brassica oleraceae
Calabash gourd-see Lagenaria vulgaris
Capsicum annum (pepper) Myzus persicae Sulz.
Carrot-see Daucus carota
Cauliflower-see Brassica' oleraceae var. botrytis
Chenopodium viride (Lamb's quarters)
Myzus persicae Sulz.
1 Credit for the determinations of many of the aphids listed herein is given to
J. J. Davis, Edith M. Patch, and F. B. Paddock.

FALL NUMBER

Chloris gavana (Rhodes grass) Macrosiphum sp.
Sipha flava Forbes
Chrysanthemum sp. (Chrysanthemum)
Macrosiphum sanborni Gill.
Citrullus vulgaris (watermelon) Aphis gossypii Glov.
Citrus aurantium (orange) Aphis gossypii Glov.
Myzus persicae Sulz.
Toxoptera aurantii Koch.
Collards-see Brassica oleraceae var. acephala
Corn-see Zea Mays
Cotton-see Gossypium herbaceum
Cucumis sativus (cucumber) Aphis gossypii Glov.
Cucumis sp. (musk-melon) Aphis gossypii Glov.
Cucurbita sp. (squash) Aphis gossypii Glov.
Cyperus esculenta (nut grass) Carolinaia sp.
Sipha flava Forbes.
Daucus carota (carrot) Myzus persicae Sulz.
Easter lily-see Lillium longiflorum
Egg-plant-see Solanum melongena
English ivy-see Hedera helix
Euphorbia pulcherrima (poinsettia) Myzus persicae Sulz.
Gnaphalium spathulatum Aphis gossypii Glov.
Macrosiphum rudbeckiae Fitch.
Myzus persicae Sulz.
Gossypium herbaceum (cotton) Aphis gossypii
(Reported in Bul. 34, Fla.)
Grape-see Vitis sp.
Grasses
Andropogon annulatus
Andropogon barbindoes
Andropogon halepensis (Johnson grass)
Andropogon monticela
Andropogon sericens
Andropogon sp. (Soudan grass)
Anthephora hermaphrodita
Cenchus biflorus
Chaetochloa flava
Chaetochloa aurea
Eleusine coracana
Eragrostis eurouloa
Eulalia japonica zebrina
Melinis multiflora
Panicum antidoldes
Panicum maximum
Panicum hirsutissimum
Paspalum nodosum
Paspalum stoleniferum
Pennisetum glaucum
Pennisetum spicatum
Pennisetum typhoideum

THE FLORIDA ENTOMOLOGIST

Sorghastrum stipoides
Syntherisma consanguinea
Tricholaena rosea (Natal grass)
Tricholaena wrightii

Green briar-see Smilax sp.
Hedera helix (English ivy)

Helianthus annuus (sunflower)
Hickoria alba

Hickoria pecan (pecan)
Hickoria sp. (hickory)

Moonflower-see Ipomoea pandurata
Musk-melon-see Cucumis sp.
Mustard, black-see Sinapis nigra
Nut grass-see Cyperus esculenta
Oats-see Avena sativa
Okra-see Hybiscus esculentus
Orange-see Citrus aurantium
Pansy-see Viola tricolor
Parsnip-see Pastinaca sativa
Pastinaca sativa (parsnip)
Pea-see Pisum sativum
Peach-see Prunus persica
Pecan-see Hickoria pecan
Pepper-see Capsicum annum
Phaesolus vulgaris (garden bean)
Pine-see Pinus taeda

Sipha flava Forbes

Aphis hederae Kaltenbach.
Myzus persicae Sulz.
Myzus persicae Sulz.
Phylloxera caryae-scissa
(Reported by Pergande (30)
Phylloxera sp.
Monellia caryella Fitch.
Phylloxera sp.
Phylloxera sp.
Phylloxera sp.

Holly-see Ilex opaca
Hybiscus esculentus (okra) Myzus persicae Sulz.
Hybiscus sp. (hybiscus) Myzus persicae Sulz.
Ilex opaca (holly) Toxoptera aurantiae Koch.
Ipomoea pandurata (moonflower) Aphis gossypii Glov.
Ironweed-see Vernonia angustifolia
Kale--see Brassica oleraceae var. acephala
Kohl rabi-see Brassica oleraceae var. caulo-rapa
Lactuca sativa (lettuce) Macrosiphum rudbeckia- Fitch
Myzus persicae Sulz.
Lagenaria vulgaris (calabash gourd) Aphis gossypii Glov.
Lamb's quarters-see Chenopodium viride
Lettuce-see Lactuca sativa
Lillium longiflorum (Easter lily) Aphis gossypii Glov.
Myzus persicae Sulz.
Lycopersicum esculentum (tomato) Megoura solani Thomas
(Reported Fla. Bul. 125)
Myzus persicae Sulz.

Myzus persicae Sulz.

Myzus persicae Sulz.

FALL NUMBER

Pinus taeda (pine) Lachnus pini L.
Pisum sativum (garden pea) Macrosiphum pisi L.
Myzus persicae Sulz.
Poinsettia-see Euphorbia pulcherrima
Potato-see Solanum tuberosum
Prunus persica (peach) Myzus persicae Sulz.
Pyrus malus (apple) Aphis pomi DeG.
Radish-see Raphanus sativus
Raphanus sativus (radish) Myzus persicae Sulz.
Rhodes grass-see Chloris gavana
Rosa sp. (rose) Macrosiphum davisi Del G.
Rose-see Rosa sp.
Saccharum officinarum (sugar cane) Sipha flava Forbes
Sinapis nigra (black mustard) Myzus persicae Sulz.
Smilax sp. (green briar) Pemphigus attenuatus Osb.
Solanum melongena (egg-plant) Myzus persicae Sulz.
Siphonophora curcurbitae Middleton.
(Reported from Bul. 34, Fla.)
Solanum tuberosum (potato) Myzus persicae Sulz.
Sonchus asper (spiny-leaved sonchus)
Rhopalosiphum sonchi Oestlund,
Sonchus oleraceus (sow thistle) Rhopalosiphum sonchi Oestlund.
Sophia pinnata (Tansy mustard) Myzus persicae Sulz.
Sorghum-see Andropogon sorghum
Sow thistle-see Sonchus oleraceus
Squash-see Cucurbita sp.
Stizolobium deeringianum (velvet bean)
Myzus persicae Sulz.
Sugar cane-see Saccharum officinarum
Sunflower-see Helianthus annuus
Tansy mustard-see Sophia pinnata
Tomato-see Lycopersicum esculentum
Turnip-see Brassica rapa
Velvet bean-see Stizolobium deeringianum
Vernonia angustifolia (Ironweed) Aphis vernoniae Thos.
Viola tricolor (pansy) Myzus persicae Sulz.
Viola sp. (violet) Myzus persicae Sulz.
Violet-see Viola sp.
Virginia creeper-see Ampelopsis quinquefolia
Vitis sp. (wild grape) Macrosiphum viticola Thos.
Watermelon-see Citrullus vulgaris
Zea Mays (corn) Aphis maidis Fitch
(Reported in Fla. Bul. 2)
Aphis .setariae Thos.
Macrosiphum sp.
Myzus persicae Sulz.
Sipha flava Forbes.
Toxoptera graminum Rond.

- 25

THE FLORIDA ENTOMOLOGIST

MINUTES OF MEETINGS
LANGUAGE HALL, April 25, 1921.
Society called to order 4:30 p. m. President Watson in the
chair. The paper of the evening was "Fungus Enemies of the
Walnut Aphis," by Dr. O. F. Burger. The paper was very in-
teresting and highly appreciated by all present..
Under Timely Notes, Dr. Montgomery stated that the Pink
Boll Worm had been found on four islands of the West Indies.
Mr. Stirling spoke of a new insect that had been reported as
doing considerable damage to cotton in Mexico.
J. Chaffin reported considerable damage being caused by
orange leaf notcher (Artipus floridanus) and Blue Green Citrus
Beetle (Pachnaeus opalus) to citrus and avocado in vicinity of
Little River.
There being no further business, the society adjourned.
J. CHAFFIN, Secretary.

DEFERRED MEETING OF JULY 11, 1921
Meeting was called to order at 4:45 by Prof. J. R. Watson,
the president, in the chair. Mr. Chamberlain, in charge tobacco
insect investigations for the Bur. Ent., U. S. D. A., at Quincy,
Fla., was elected to membership.
Prof. Fattig, the vice president of the Society, having left the
State permanently, this office was declared vacant by a vote of
the Society, and Mr. A. C. Brown elected by acclamation to fill
this vacancy.
It was voted to omit the regular July and August meetings
and have the next meeting in September.
There were present: J. R. Watson, Geo. B. Merrill, A. H.
Beyer, A. C. Brown, J. C. Goodwin, J. H. Montgomery, F. M.
O'Byrne, and E. W. Berger.
The paper of the evening was by Mr. A. H. Beyer, Asst. Ento-
mologist at Experiment Station. Subject: Coccobacillus acri-
diorum as a Factor in Locust Control. Mr. Beyer's paper con-
sisted of a discussion of his work on this bacterium while he
was in the employ of the U. S. D. A. in 1919. The paper was
of great interest and a brief resume by the author is attached
to these minutes.
Under Brief and Timely Notes Prof. Watson showed a bag-
worm and also a large thrips.
The Society adjourned at 6 p. m.
E. W. BERGER, Secretary pro-tem.

FALL NUMBER

October 5, 1921.
A special meeting arid smoker of the Florida Entomological
Society was called to order at 8:30 p. m., President Watson in
the chair. Members present: Berger, Briggs, Brown, Burger,
Chaffin, DeBusk, Goodwin, Hunt, Merrill, Mason, Newell, Mont-
gomery, Reese and Yothers. Several visitors and speakers of
the Citrus Seminar were also present.
The president welcomed the visitors and made a few intro-
ductory remarks, after which business was taken up in the reg-
ular order. On motion and second E. L. Lord, Assistant Pro-
fessor of Horticulture in the Agricultural College, was duly
elected a member of the society.
Mr. W. W. Others of the Bureau of Entomology was called
on for a few remarks and he gave a very interesting account of
some of the work and experiments he is carrying on at Orlando
in the control of citrus insect pests. He spoke of the difficulty
of rearing rust mites in confinement and of controlling the Fla.
Red Scale (Chrysomphalus aonidum). He stated that he had
found a 2% emulsion of a heavy viscid oil satisfactory.
Dr. H. A. Morgan, president of the University of Tennessee,
was then called upon. He gave a very humorous and interesting
talk on his experiences as an Entomologist in Louisiana twenty
or thirty years ago. He also gave a brief account of his work
in distributing a parasite of the Harlequin Cabbage bug and his
efforts in helping secure the first Government appropriation
for the eradication of- the cattle tick.
Mr. Neal F. Howard of the Bureau of Entomology next gave
some interesting facts in regard to the Mexican bean beetle sit-
uation in Alabama and Georgia.
On motion of Dr. J. H. Montgomery, the Society passed the
following resolution:
"Whereas, the attention of the Society has been directed to
work done by Dr. A. T. Speare of the Bureau of Entomology in
connection with fungi preying upon mealybugs and rust mites,
and
"Whereas, the results so far obtained are extremely promis-
ing and indicate that a natural control of these pests may be
found to be of practical value, and
"Whereas, in the opinion of the Society, this work should be
prosecuted vigorously and without interruption,
"Therefore, Be it resolved by the Florida Entomological So-
(Continued on page 30)

Bhe
FLORIDA ENTOMOLOGIST
Official Organ of The Florida Entomological Society, Gainesville,
Florida.

PROFESSOR J. R. WATSON-..-.....--- .......................--..--.....- -Editor
DR. WILMON NEWELL......--...................-------..........Associate Editor
DR. E. W. BERGER....-...................-....................... Business Manager
Issued once every three months. Free to all members of the
Society.
Subscription price to non-members is $1.00 per year in ad-
vance; 25 cents per copy.

ENTOMOLOGICAL PAPERS AT THE CITRUS SEMINAR
On Oct. 5 Mr. W. W. Others fead a paper on "Some Funda-
mentals of Grove Pest Control." He stated that there are three
possible viewpoints: (1) To do nothing, leaving the control of
the pests to their natural enemies. (2) To take such measures
as will reduce their numbers to the point of commercial control.
This will necessitate frequent repetitions of the control mea-
sures. (3) To eradicate the pest-expensive in the first costs
but perhaps often cheapest in the end. Which method should
be pursued will depend upon the insect. Or a combination of
the methods will often be most practical.
Mr. Others also read a very valuable paper by Dr. A. T.
Speare of the U. S. Bur. of Ent., founded on work done in Mr.
Others' laboratory at Orlando. It has long been a matter of
common observation that the citrus rust mites and mealy bugs
tend to disappear with the advent of the rainy season. It has
been generally supposed that this was due to their being washed
off by the heavy rains. But according to Dr. Speare the true
cause is the rapid development of two fungi under the influence
of the high humidity of the rainy season. The fungus which
infects the rust mites is a species of Cordiceps. Infected rust
mites may be recognized by their shrunken appearance and of
course absence of movement. The fungus which attacks the
mealy'bugs is an undescribed species of Entomophora. Infested
mealy bugs may be recognized by their soft spongy texture.
Under a sharp knife they can be cut like cheese.
These discoveries are not only of great scientific interest but
of equal practical importance. If a grower finds that one of
these fungi is rapidly developing in his grove, under suitable
28

FALL NUMBER

weather conditions he may often safely leave the control of the
pest to the fungus, and save the cost of spraying.
Another paper on entomogenous fungi was read by Dr. E. W.
Berger, who gave a brief account of his growing, in pure cul-
tures, of two fungi hitherto not so grown and of his discovery
of a new strain of the Red Whitefly-Fungus.
The new fungi are Aschersonia goldiana on Cloudy-winged
Whitefly from Cuba (specimens received at the Experiment Sta-
tion) and on an unknown aleyrodid from Winter Park, Florida;
and the Cuban Aschersonia found infecting the Pyriform Scale,
and Liriodendron Scale in Florida, and the Tessellated Scale in
Porto Rico.
The new strain of the Red Whitefly-Fungus was discovered
on some holly and bay leaves sent in from a hammock at Winter
Park, Fla. It fruits freely in the culture bottles during summer,
a fact which has not been true for the other strains heretofore
grown. This fact will make it possible to grow it in smaller
quantities during summer as needed, thus always assuring a
fresher product than heretofore when the whole crop had to
be grown in late winter and early spring and kept in cold stor-
age. Indications are that it is also an unusually virile strain.
Prof. J. R. Watson presented the results of some recent ex-
periments on spraying for thrips. He exhibited a table giving
the results of spraying to lessen thrip marks on fruit. This
covered the results in seven groves from Lake to St. Lucie
counties. In groves where the thrips averaged from 25 to 64
per bloom, about half of the unsprayed fruit was marked to
such an extent as to lower its grade from brights to golden if
otherwise perfect. 38% of this scarring was prevented by a
single spraying. This repaid the cost of spraying many times
over. Groves in which the thrips averaged 10 per bloom did
not repay the cost of spraying for thrips alone. But where they
were being sprayed at blossoming time for rust mite or scab the
additional cost of adding 3/4 pt. of Black Leaf 40 per 100 gallons
was repaid twice over.
The proper time to spray is when the trees are in full bloom,
and the proper solution at least 1 pt. of Black Leaf 40 to 100
gallons of the rust mite spray solution.
Mr. Neal F. Howard gave an interesting account of the Mexi-
can Bean Beetle investigations of the Bur. of Entomology, U. S.
D. A., in Alabama, Georgia and Tennessee. There appears to be
no hope of stopping the beetles and growers of legumes will have

30 THE FLORIDA ENTOMOLOGIST

to plan substituting other crops and immune species. Fortu-
nately, the velvet bean, both bush varieties and climber, are
immune, except that the adult beetles do feed some upon them,
so that this.bean may have to be substituted as a cover crop and
forage in place of cow peas and beggar weed. Snap beans appear
doomed. The use of poisons in its control have proved unsatis-
factory. Investigations in Mexico, in search of natural enemies,
have so far been fruitless.
Mr. Chaffin read a paper on mealy bugs. This is printed
elsewhere in this journal.

MINUTES OF MEETINGS
(Continued from page 27)
city, in special session at Gainesville October 5, 1921, that Dr.
Speare be congratulated upon the success which has so far at-
tended his efforts, and
"Further, That the Secretary of the Society communicate with
the Chief of Bureau of Entomology expressing the hope of the
Society that Dr. Speare will be assigned to further investiga-
,tional work in Florida to the end that this work be completed."
There being no further business, the Society adjourned.
J. CHAFFIN, Secretary.

PERSONALS
Among our out of town members present at the Citrus Sem-
inar were W. W. Others and A. C. Mason of the U. S. Ent. Lab.
at Orlando; E. F. DeBusk, County Agent of Lake; W. R. Briggs,
Agent for Manatee County; Mr. Seth Walker of the Citrus Ex-
change; Mr. K. E. Bragdon, formerly County Agent of Brevard
but now Field Agent with the Citrus Exchange Supply Co.;
and Mr. C. M. Hunt, Assistant Nursery Inspector.
Miss Evelyn Osborn, formerly Assistant in Entomology in
the Experiment Station, was on Aug. 27 married to Mr. Chas.
M. Knapp of Syracuse, N. Y.
Prof. Carl J. Drake received the degree of Ph. D. from Ohio
State University in June. He has been spending the summer
in Mississippi, Arizona, and California.
W. S. Blatchley received the degree of LL. D. from the Uni-
versity of Indiana in June. Dr. Blatchley is one of less than
a dozen to receive this degree from Indiana University. He
expects to return to his winter home in Dunedin shortly.

FALL NUMBER

The stork has recently visited the homes of two of our mem-
bers, Mr. Geo. Merrill and Mr. W. W. Others. Both girls.
Mr. P. W. Fattig is now teaching biology in the State Normal
School at Farmville, Va.

MEALYBUGS
By JEFF CHAIN
Mealybugs are one of the most widely distributed group of
insects known; they occur in practically every country in the
world and attack nearly every cultivated and wild plant. If it
were not for the fact that they have a large number of natural
enemies they would no doubt do serious damage to many of our
most valuable crops. They seem to thrive best and do the most
damage in tropical and subtropical climates. We probably have
forty or fifty different species in this State, but of that number
there are only three or four that do very much damage. How-
ever, many of the most injurious species have not been intro-
duced into Florida.
One species that we do not have does serious damage to
sugar cane in Cuba. California has two species that do consider-
able damage: Baker's mealybug which attacks the grape, and the
citrophilus mealybug which prefers citrus. They have made
several unsuccessful efforts to control and eradicate these pests.
These two species are probably the most injurious mealybugs
in the United States and neither of them is present in Florida
at the present time. There are no doubt many other species
in the United States, as well as in the tropical countries, that
would do serious damage if brought to this State.
The mealybug that does the most damage in Florida at the
present time is the Common Citrus Mealybug (Pseudococcus
citri) which is a serious pest in our ornamental nurseries and
greenhouses and sometimes becomes very numerous in citrus
groves during dry seasons. During the dry spell last summer
they did more damage than usual all over the citrus belt. This
particular species is present all over the United States but it
seems to do the most damage here. We do not hear of it causing
any damage in California, so either their climatic conditions are
unfavorable for it or they have some natural enemy that we do
not have.
The next of importance is the Cocoanut Mealybug (P. nipae)
which is always present on trees and ornamentals in the south-
ern part of this State. During the dry spell last summer the

THE FLORIDA ENTOMOLOGIST

avocados, mangoes, sapodillas, palms, many other ornamental
plants in Fort Myers were covered with this insect. The sooty
mold, growing on the honey dew excreted by the pest, made a
very unsightly appearance and, of course, the fruit and plants
were damaged. This species apparently does not have as many
natural enemies as the common citrus mealybug and is just as
hard if not harder to control.
Another species that is beginning to play an important part
is the Pineapple Mealybug (P. bromeliae) which did quite a bit
of damage to several pineapple plantings down the east coast
this year. This pest prefers the pineapple and was probably
brought to this State several years ago on imported pineapple
slips.
The life cycle of a mealybug is short and a female will lay
from three to five hundred eggs; so if conditions are favorable
it takes only a short time for them to become very numerous
regardless of the fact that they have a large number of natural
enemies. They have insect friends that protect them and aid in
their multiplication. Several species of ants will carry the
young mealybugs around and protect them in order that they
may secure the honeydew secreted by the pest. The most active
ant along this line is the Argentine ant, which we do not have
in this State at the present time.
Owing to the large number of host plants, rotation of crops
would do very little good in the control of mealybugs. Some of
the most important natural enemies are some hymenopterous
parasites, lady beetles and the larvae of syrphid and lace-wing
flies.
Mealybugs are covered with a wax-like secretion and the eggs
are deposited in a mass of this material, so spraying with a
strong insecticide has very little effect. When the rainy season
begins, the severe infestations disappear, so spraying with clear
water under high pressure to wash the insects from the tree has
been recommended by the best Entomologists for years, but any-
one who has had much experience spraying for mealybugs knows
that any kind of solution or pressure gives very poor results.
Quite recently one of the field men of the. Bureau of Ento-
mology discovered an unnoticeable fungus attacking the mealy-
bug and when the rainy season began this year this fungus com-
pletely destroyed the severe infestations in several groves that
he had under observation. Personally, I believe their disappear-
ance during rainy weather is due to this fungus rather than the

FALL NUMBER

rain. If this is the case, our problem is to induce this fungus
to thrive during dry weather or find some parasite that will
hold the mealybug in check until the rainy season begins.

IT PAYS TO CONTROL RUST MITE
J. G. GROSSENBACHER
Strange to say, the rust mite is not an insect but is more
closely related to spiders. It is a near kin of the itch mite,
"red bugs," red spiders, and cattle ticks. It feeds on all new
green growth of trees: leaves, fruit and twigs. It seems to live
on juices taken from trees, particularly the oil. However, if
these mites consumed all the oil from the glands they open we
would have no real rusty fruit. In fact, the rusty appearance
of fruit, leaves and twigs is due to the oil oozing from glands
that had been tapped by the mites. The oil flowing from the
punctured glands spreads out more or less over the rind of the
fruit and during nights of heavy dew or light showers may run
down the sides of the fruit in narrow bands; the exposure of
these thin layers of oil to the air causes the oil to break down
or oxidize and change to a dark color, thus resulting in rust and
where it had run down the fruit in streaks to "tearstaining."
There is another effect that the exuding oil has on young fruit
and other newly developed parts of trees that should be men-
tioned in this connection. In 1914 and 1915, I punctured a large
number of oil glands on newly hardened young twigs and half-
grown oranges with a very fine pointed needle under a lens.
The punctured areas were marked and kept under observation
during some weeks. Small amounts of oil escaped from each
pricked oil sack and spread over tiny spots and areas, the shape
of which depended upon the action of gravity on the escaping
oil. After a few days the distribution of the oil was definitely
and clearly shown by brown spots of the exact size and shape of
the oil-covered area. In order to make a further test of the
effects of orange oil on the epidermal tissues of fruit, leaves
and twigs of orange and grapefruit, a small quantity of this oil
was obtained and applied with an atomizer so as to cover the
surface with tiny spots of oil; in other cases the application was
continued until the oil spots became so numerous and close to-
gether that they eventually touched and thus covered consider-
able areas completely with a continuous film of orange oil. The
result was interesting in that in case of the light applications
every point, formerly occupied by oil-dust particles delivered by

THE FLORIDA ENTOMOLOGIST

the atomizer, was shown by a tiny brown spot. Where the ap-
plications had been so heavy that considerable areas were cov-
ered with a continuous film, these areas showed up of the same
size and shape as brown blotches. On closer examination the
outer skin of these oil covered spots was found to have been
killed, leaving a rough outer surface consisting of broken, dead
skin tissue adhering to an imperfect substitution skin under-
neath. In a few cases of extra heavy application of orange oil
the entire bark was killed to the wood on twigs as large as a
lead pencil, thus resulting in the death of the twigs.
In making these tests with needle pricks and atomizer, I was
trying out a suspicion that melanose and ammoniation spots
may be due to the bursting of oil glands and the consequent
exudation of their contents to the outer surface where the effect
of the oil would damage the epidermal layer or outer skin of
newly grown leaves, fruit, and twigs. It is evident that the oil
is a factor in the development of melanose and ammoniation or
dieback spots but the reasons for the escape of the oil from the
sacks to the outside must be found before a full explanation can
be given. In case of the disease known as melanose it appears
that probably abortive infections from spores- of the stem-end-
rot fungus permit the leakage of the oil and thus result in
melanose spots..
Coming back now to the appearance we call rust, one need
only examine a very rusty orange that had an early infection,
with a hand lens, to see that the outer skin has been killed and
that its broken fragments are adhering to an imperfect inner
one. This is true only of russeting that is due to an early attack
of rust mites on fruit. In case rust mite does not become very
numerous until after the fruit has attained considerable size,
however, the oil injury following is not so serious and usually
gives rise to smooth russets. The rough russets .due to the early:
attacks of rust mites are commonly called buck-skin or shark-
skin fruits.
The effects, then, of rust mite on fruit are considerable and
various, depending upon the relative earliness and intensity of
the infestation and on the weather conditions prevailing during
the period of greatest activity. For example, tear-staining can
probably result only during periods of comparatively dry weather
so that the exuded oil accumulating in spots of intense mite.
activity may be carried down the sides of fruit in streaks by
dew deposits thus allowing concentrated action of the oil, while

FALL NUMBER

rains probably dilute the oil to such a degree and wash it off
so quickly that no discoloration can result in streaks. Again, a
comparatively late attack of the mite will result only in smooth
russets and practically no buck-skin effects. In any case, how-
ever, it is evident to everyone who observes the presence and
activities of the enormous numbers of mites on heavily infested
trees that the devitalizing effects of this pest on trees must be
more in proportion to their numbers than to their size.
The immediate and most striking loss to growers due to the
unhindered development of rust mites in bearing groves is of
two kinds: the discoloration of the rind of fruit, and stunting
effect on the fruit growth occasioned by the injuries on the
rind. The devitalizing effects on trees necessarily also affects
fruit size but probably tells heavier on the performance of trees
the following season.
(Excerpt from Citrus Leaf No. 7, published May 1, 1921, by the Florida
Insecticide Company, Apopka, Florida.)

The negro caretaker of the Reid Bryan nursery reports that
he has sprayed every month with "miserable oil." Some of it
is, we'll say! .

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