Suppose you were not well acquainted with entomology, and you heard some friends talking about “wheel bugs”. Although you had no idea what such a creature might be, if you saw a photograph such as the one below, you might be able to guess that it depicts a “wheel bug” (Arilus cristatus). The ornate cogged crest on its thorax is only found on this one species of the insects occurring in the U.S.

I found this one dead on my deck. It is pretty intact except for some broken off antennae.

Wheel bugs are part of a group of insects called “Assassin Bugs”, and they are voracious predators, mainly of other insects. Their mouth parts have been fused together during evolution to form a long hollow tube. This can be seen in this specimen where it is folded back under the head. Wheel bugs kill such prey as caterpillars by stabbing them with this organ, then secreting digestive enzymes into the prey. When digestion has proceeded, the wheel bug can siphon nutrients back up into itself. Wheel Bugs mostly prey at night on sleeping victims. Their large eyes probably help with night vision. Wheel Bugs are regarded as beneficial since they prey on many insect pests of agricultural and horticultural crops. They are one of the few insects to prey on Brown Marmorated Stinkbugs (Halyomorpha halys, which have recently become a pest in parts of the U.S.).

Incidentally, Wheel Bugs can inflict a painful sting, so be careful handling them.

Wheel