ENTFACT-426: The Wheel Bug  |  Download PDF

by Ric Bessin, Extension Entomologist
University of Kentucky College of Agriculture 

Wheel Bug Adult

The wheel bug (Arilus cristatus L.) is a large insect (1-1/4 inches) found in meadows and on trees and shrubs throughout Kentucky. This insect is common throughout the year, but the adult stage may be seen in the late summer. There is a single generation per year in Kentucky. It gets its common name from the appearance of a cog-like wheel emerging from the top of the thorax. Adult wheel bugs are commonly attracted to lights at night near wooded areas. 

The wheel bug is a true bug and has a stout beak that it uses to feed. It belongs to a group of bugs called the assassin bugs. It is the largest of the assassin bugs in Kentucky. These are insect predators that feed on caterpillars, moths, and other soft bodied insects. The front legs are enlarged and used to seize and hold its victims. The wheel bug then inserts its beak into its prey to drain the body fluids. These insects are considered beneficial in the garden and wooded areas, as they reduce the numbers of some insect pests. 

At first sight wheel bugs appear to be a dangerous insect because of their size and weird appearance. But it is not aggressive and will try to avoid contact. However, if handled the wheel bug will try to bite. The author notes that the bite is painful, with the sensation lasting several minutes. 

Wheel Bug Nymph

In the fall, the female wheel bug lays her eggs on small twigs of shrubs and trees. There are several dozen of these barrel-shaped eggs in a cluster. In the early spring, the eggs hatch and small red and black nymphs with long legs disperse onto surrounding trees and shrubs. Homeowners may see these on various trees or landscape shrubs. 

Issued: 7/96 
Revised: 11/03

CAUTION! Pesticide recommendations in this publication are registered for use in Kentucky, USA ONLY! The use of some products may not be legal in your state or country. Please check with your local county agent or regulatory official before using any pesticide mentioned in this publication. 


Photos: Ric Bessin, University of Kentucky Entomology