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WHEEL BUG

James R. Baker and S. Bambara, Extension Entomologists

CAUTION: This information was developed for North Carolina and may not apply to other areas.

WHEEL BUG, Arilus cristatus (Linnaeus),, Reduviidae, HEMIPTERA

General Information

Wheel bugs are large (up to 1-3/8 inches), brown to gray bugs with a dark, shining area of the wings over the rear of the body. Antennae are thin and rusty brown. There is a conspicuous raised half "cogwheel" on the thorax. Adults are striking red when they first present, but soon take on the cryptic gray coloration. Young bug nymphs are bright red with black markings, whereas older nymphs are colored like adults. Nymphs grow from about 1/8 to 1 inch. The eggs are dark brown and about 1/8 inch long with a tan rim around the top. The top has a dark brown center. The egg is bottle shaped and is glued down in a mass of 42-182 eggs which forms an irregular, raised patch.

Biology

Wheel bugs occur throughout North Carolina. They feed voraciously on caterpillars, such as the fall webworm and imported cabbageworm. Wheel bugs have been reported to feed on locust borer adults on goldenrod, Japanese beetles, eleven-spotted cucumber beetles, leafmining beetle larvae inside the leaf and other insects. Female wheel bugs sometimes kill and feed on male wheel bugs after mating. Wheel bug nymphs feed on aphids and other small insects.

Wheel bugs feed by piercing the host and injecting a potent saliva into the prey. The saliva contains enzymes that quickly subdue the prey and then digest the tissues inside. The wheel bug then sucks this digested liquid from the prey as it shrivels up. If handled carelessly, wheel bugs may inflict a painful bite on people. Such a bite has been described as "much more powerful than a hornet or wasp sting". Injury from a wheel bug bite takes about 10 days to heal and leaves a small scar.

Female wheel bugs lay masses of 42-182 eggs by gluing them to bark or some object. Wheel bugs overwinter as eggs. Tiny wheel bug nymphs hatch in April and May and begin to feed on aphids and other small insects. As nymphs develop through five instars (stages), they become larger and thus capable of attacking larger prey. Adult wheel bugs feed on large hornworm caterpillars. There is one generation per year. Perhaps because wheel bugs feed on other insects, they are not usually extremely abundant. When prey is scarce, wheel bugs feed on other wheel bugs, and female wheel bugs commonly feed on male wheel bugs after mating. Because of their large size and bizarre half "cogwheel" on the thorax, wheel bugs are commonly collected by homeowners and children and are then submitted for identification. Fortunately most amateur collectors are sufficiently impressed by the ferocious appearance of wheel bugs to avoid being bitten.

Control

Because wheel bugs prey upon plant pests and because wheel bug numbers are usually low, control of wheel bugs is not warranted. Direct handling of wheel bugs should be avoided since they can inflict a painful bite. If these bugs are a nuisance, they can be safely dislodged with a stick, brush or some other object and relocated.

REFERENCES

Readio, P.A. 1927. Studies on biology of the Reduviidae of America north of Mexico. Univ. Kansas Sci. Bull. 17, 291 pp.

Slater, J.A. and R. M. Baranowski. 1978. How to know the true bugs. William C. Brown Co., Dubuque, IA, 256 pp.


For assistance, contact your county North Carolina Cooperative Extension Service agent.

Other Resources

Prepared by: James R. Baker & S. Bambara, Extension Entomologists
Some photographs contributed by Dianne L. Roman.

Published by North Carolina Cooperative Extension Service

Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914. Employment and program opportunities are offered to all people regardless of race, color, national origin, sex, age, or disability. North Carolina State University at Raleigh, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.
© 2001 NC Cooperative Extension Service

ENT/ort-65 July 1994 (Revised)May 1997
Web page last reviewed January, 2011 by the webperson.