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.
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.
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.
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.
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