(Order Hemiptera, Family Reduviidae)
Arilus cristatus mating on Black Ash leaves (photo by Rachel Stone)
(Kansas: Sedgwick County. Pawnee Prairie Park, 37° 39' 18'' N, 97° 27' 18'' W. September 15, 2013.)
The distinguishing characteristic of the adult Wheel Bug is its pronounced pronotum arising into a cog-like "wheel" crest along the midline. The species is the largest true bug in Kansas and ranges from 28 to 36 mm long. The body is stout and brown-gray to black with the membranous portion of its hemelytrous forewing coppery in color. The antennae are long, slender, and reddish-brown. When not feeding, the 3-segmented beak is tucked away in a crevice before the forelegs called the stridulatory groove. Males are smaller than their female counterpart, but otherwise both sexes look very similar.
Nymphs are blood-red with black markings. They lack the distinctive pronotum "wheel", and the posterior portion of the abdomen points upward.
Arilus cristatus nymph (from: http://entnemdept.ufl.edu/creatures/trees/wheel_bug.htm).
Adults and nymphs alike are predatory and generally considered to be beneficial, as they play an important role in pest control. The species is diurnal, but is known to show up at lights opportunistically to prey upon the insects that are attracted.
It is best to avoid careless handling of the Wheel Bug; it is known to readily give a painful stab when defending itself. The species is also capable of giving off a pungent odor from scent sacs on the apex of its venter.
Arilus cristatus has one generation per year. Adults can be found from May to November. After mating, the female will deposit her eggs in clusters upon foliage. The eggs will overwinter, and nymphs emerge the following spring, undergoing 5 molts before they reach their adult stage by summer.
Arilus cristatus is widely distributed in Kansas. It is commonly found in the eastern United States.
Distribution of Arilus cristatus in the United States (Map created by: http://bugguide.net/node/view/454/data).
Arilus cristatus is an active predator and will prefer to be wherever its prey is most abundant. Within its ranges, it can commonly be found in meadows and on field crops.
Wheel Bug adults and nymphs are not picky eaters. They preferentially feed on soft-bodied insects such as caterpillars and aphids, but it is not uncommon to find them feeding on bees, sawflies, and even beetles.
Conservation Status: Stable
Wheel Bug Kills Stink Bug
Bug Guide: Species Arilus cristatus - Wheel Bug: http://bugguide.net/node/view/454
Encyclopedia of Life: Species Arilus cristatus - Wheel Bug: http://eol.org/pages/609871/overview
American Insects: Species Arilus cristatus - Wheel Bug: http://www.americaninsects.net/ht/arilus-cristatus.html
Milne, L. and M. Milne. 1980. National Audubon Society Field Guide to North American Insects and Spiders. Random House, Inc., New York, NY.
Salsbury, G.A. and S.C. White. 2000. Insects in Kansas. Kansas Department of Agriculture.
Triplehorn, C.A. and N.F. Johnson. 2005. Study of Insects, 7th Edition. Brooks/Cole, Cengage Learning, Belmont, CA.
Submitted by: Rachel Stone, November 2013