Ensign Wasps

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Ensign Wasps
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Brambila, J.
University of Florida Cooperative Extension Service, Institute of Food and Agriculture Sciences, EDIS
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Gainesville, Fla.
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Collected for University of Florida's Institutional Repository by the UFIR Self-Submittal tool. Submitted by Melanie Mercer.
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"First published July 1996. Revised July 1997"
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1. This document is ENY -280, one of a series of the Entomology and Ne matology Department, F lorida Cooperative Extensi on Service, Institute of F ood and A gricultural Sciences, University of F lorida. First published Ju ly 1996. Revised Ju ly 1997. P lease visit the ED IS Web site at http://edis.ifas.ufl.edu. 2. J Brambila, research assistant and P .G. Koehler, profess or/extensi on entomologist, Entomology and Ne matology Department, Cooperative Extensi on Service, Institute of F ood and A gricultural Sciences, University of F lorida, Gaines vi lle, 32611.The Institute of Food and Agricultural Sciences is an equal opportunity/affirmative action employer authorized to provide rese arch, educational information and other ser vices only to individuals and institutions that function w it hout regard to race, color, sex, age, handicap, or national origin. For information on obtaining other extension publications, contact your county Cooperative Extension Service office. Florida Cooperative Extension Ser vice / Institute of Food and Agricultural Sciences / University of Florida / Christine Ta ylor Waddill, DeanFigure 1 Ensi g n wasp.ENY-280Ensign Wasps1J. Brambila and P.G. Koehler2Ensi gn wasps are small, spider -like black insects conspicuous. The males are si milar to the females, that occasionall y fl y into or live in homes, warehouses, except for a smaller abdomen. or other buildin gs. They do not stin g or bite humans or their pets or cause any damage indoors, so their presence should not be of concern. The fe male adult la ys her eggs in the oothecae of cockroaches, parasitizing them. These insects, therefore, are beneficial to us. Ensi gn wasps belong to a group of insects called Evaniidae, or evaniid wasps. They are called ensi gn wasps because they have a small, compressed, black abdomen that they often mo ve up and down (it seems as if the y were signalin g with a small fla g). Sometimes they are thought to look like spiders because of their black color and their relati vel y long le gs on a stout thorax. Adult ensi gn wasps (Fi gure 1) are usuall y entirely black in coloration. The y have three pairs of le gs, two pairs of wings, and are 1/4 to 3/4 inch long with a general body shape that makes them easily distin guishable fro m other wasps. They have a broad head, a stout thorax, and a small, laterally compressed oval or somewhat triangular abdomen that is attached hi gh on the thorax by a narrow, c ylindrical petiole, instead of down near the bases of the hind legs. The ovipositor is occasionallyDistributionAbout 400 species of evaniids have been described, bein g most abundant in the tropics with a few species bein g cosmopolitan. Eleven species are known to occur in the U.S. and Canada, six within Florida Evania appendigaster is the most conspicuous of these two species, bein g the largest of all the eleven species in U.S. and Canada (fore wing 1/4 to 1/3 inch in length). It has a cosmopolitan distribution, thought to have been introduced into the United States via ships hundreds of years ago along with their hosts, cockroaches of the genus Periplaneta Several species of Periplaneta invade houses, some of the most common bein g the American cockroach, P. americana, Australian cockroach, P. australasiae brown cockroach, P. brunnea and smoky brown cockroach, P. fuliginosa The American cockroach is about 1 to 1 3/4 inches long and reddish brown to dar k brown with well -developed win gs. The y la y twelve e ggs, which the y protect in a capsule glued to objects in a protected place.BiologyEvaniids are solitary wasps that are said to be predatory, but in reality the y are parasitic since they develop inside egg cases of cockroaches. Their t ypical habitat is outdoors on the forest floor, tree holes, piles of wood, and pal m bracts, where most cockroaches deposit and conceal their oothecae; however, E.


Pa g e 2 Ensi g n WaspsJuly 1997appendigaster, the most conspicuous evaniid found inside homes in Florida, parasitizes the e gg cases of the home-infestin g American cockroach and so it is found indoors, where these cockroaches often occur. Females lay a single egg in each ootheca within one of the eggs, which is the food for the first instar larva; the following four instars feed on the other eggs, eventually consumin g all of them. Pupation takes place within the ootheca, without a cocoon. At maturit y the adult cuts and escapes through a small and round but ja gged hole near one of the ends of the cockroach egg case.Pest Status and Biological Control PotentialAdults ensi gn wasps are nor mall y outdoors, are attracted to flowers and to honeydew, and live two to three weeks. They do not bite or stin g or feed on humans but they occasionall y wander indoors. Although their lar vae feed on cockroach eggs they cannot be depended upon to reduce quickl y a cockroach infestation but they help keep cockroach populations down. Their most important competitor is the Eulophid wasp Aprostocetus hagenowi i a gregarious parasitoid that has a faster development and hence more generations per year than the evaniids. However, evaniids are more efficient than A. hagenowii at locatin g well -hidden ootheca.ControlEvaniids may come into a house lookin g for cockroach e gg cases to parasitize if cockroaches are found in the area; they are most often noticed when they are at windows. Since evaniid wasps cause no damage inside the home they could be i gnored, re mo ved to the outdoors with a broom and a dustpan, or killed with a fly swatter. Host reduction ma y be helpful; elimination of hiding places, food material, and moisture sources for cockroaches will reduce the presence of the latter and of the wasps inside homes. Pesticide treatments for cockroaches, especiall y with pyrethroid insecticides, ma y kill these beneficial wasps, and so they should be li mited in their use to spot treat ments, accordin g to pesticide label directions. The best treatment for cockroaches is the preservation of beneficial insects. If a true cockroach infestation exists one could contact either the local extension agent for recommendations or a certified pest control company. Some ReferencesStange, L. A. 1978. Evania appendigaster (L.), a cockroach egg parasitoid (H ymenoptera: Evaniidae). F.D.A.C.S./D.P.I., Ent. Circ. No. 191. Mason, W. R. M. 1993. Superfamilies Evanioidea, Stephanoidea, Ma gal yroidea, and Tri gonal yoidea. In: Hymenoptera of the world: An identification guide to families. pp. 510-520. Research Branch, Agriculture Canada, Pub. 1894/E.