Don’t Handle the Wheel Bug!

By Chris Williams on November 29, 2011.

Q. My son caught this really strange looking insect. He has it inside a jar. He thinks it’s really cool because it kind of looks like a miniature dinosaur. It’s more than an inch long, kind of grayish, and has a hump on its back with a row of spines. I told him not to touch it in case it bites. He wants to take it into school for science class. Any idea what it is?

A. I think I do have an idea. This insect attracts a lot of attention because of its rather bizarre, prehistoric appearance. It’s been described as “ferocious-looking.” If you look up “wheel bug” on the Internet, I think you’ll find its match. It’s a fairly large bug, about 1-1/4 inch long, mostly gray-black, with antennae and legs tinged reddish-brown. The wheel bug gets its name from the semicircular crest on its back that has 8 to 12 cogwheel-like teeth. It looks like half of a circular saw blade or like a chicken’s comb.

wheel-bugsThe wheel bug is actually a beneficial predator, sucking the fluids mostly from plant-feeding caterpillars with its piercing, beak-like mouthparts which are tucked under its head. Wheel bugs feed by piercing the prey with their mouthparts and injecting a digestive saliva. If prey is scarce, wheel bugs will feed on each other. Like praying mantids, the female sometimes eats the male after mating. The wheel bugs is not aggressive, but your son should not handle it because it could jab him in self-defense. A wheel bug bite is described as more painful than a wasp sting with pain lasting for several hours to several days. The skin around the bite may eventually slough off.

Wheel bugs are found outside on plants where they feed on insects. They are also commonly found outside around mercury vapor lights, like those in parking lots, where they feed on the insects attracted to the lights. Wheel bugs sometimes find their way inside, often when carried in on plants. Because their coloration camouflages them, when this bizarre bug is noticed it can be a scary encounter. Wheel bugs are not very common, but it’s one of those bugs that you remember once you’ve seen it. Hopefully, when your son is done showing it around at school, he will let it go so it can go about its business of protecting plants.



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