These large bugs belong to the Hemipteran family Reduviidae which is represented in North America by over 160 different species. Members of this family are collectively known as assassin bugs; a name that clearly describes how these stealthy hunters make a living.
Wheel bugs get their descriptive common name from a peculiar morphological feature that rises from the top of the bug's thorax. The structure looks like half of a cog-wheel, with the gear teeth clearly visible. Wheel bugs are big, measuring over 1 1/4" long, and their color varies from light gray to bluish-gray to grayish-brown.