The wheel bug (Arilus cristatus) is an assassin bug and one of the largest terrestrial North American true bugs, reaching up to 38 mm in length. While they are fairly common, they are shy and have cryptic coloration so they are not often seen. The wheel bug’s name comes from the cog wheel-shaped toothed crest it sports on its first thoracic segment. These dark brown bugs are voracious predators upon many kinds of insects, including their own kind, and are helpful predators of many lepidopteran, aphid, beetle, fly and wasp pests; however they also prey on beneficial species such as ladybeetles and bees. They quickly and effectively kill their prey by secreting paralyzing saliva through their sharp mouthparts. If bothered, wheel bugs and their bright red nymphs can inflict a painful bite on humans, reportedly worse than bee, wasp or hornet stings. Adult wheel bugs make squeaking sounds, the purpose of which is unknown. When provoked, they give off a strong odor from scent glands.

(Mead 2008; WIkipedia 2011)