Looking around the garden I saw an insect I’ve never seen before. Two of them were mating on a zinnia plant. Their legs were long, almost spider-like and the head was small with a hypodermic-like mouth. But what really caught my eye was a toothed ridge on their backs that made them look like some kind of dinosaur! I grabbed the camera, got some pictures and then went searching the web to see what this bizarre insect is.
I googled “insect with ridged back” and instantly learned that this strange creature is a wheel bug (Arilus cristatus). It’s a true bug and a member of the family that includes stink bugs and bed bugs. This is the largest of the true bugs, growing up to 1 and 1/2 inches long and it gets its name because of the spiny ridge or “wheel” on its thorax. The “wheel” is only found on adult wheel bugs; nymphs lack this structure.
The wheel bug is a member of a group of bugs called assassin bugs. These predators are considered beneficial insects because they feed on many insects that homeowners and gardeners consider pests – aphids and caterpillars in particular. The way a wheel bug feeds confirms the old entomology adage that bugs suck and beetles chew. The wheel bug uses its long legs to grasp its prey. It then inserts its hypodermic-like beak to inject the prey with a substance that paralyzes it and dissolves the internal organs. The wheel bug then drains the prey of its bodily fluids. Like the adage says, bugs suck!
Wheel bugs have one generation a year. They hatch in the spring into small red and black nymphs. These nymphs molt five times and then metamorphose into adults. The adults mate and the female lays between 40-200 eggs on shrub or tree twigs. The eggs overwinter and a new generation of wheel bugs emerges in the spring.
The wheel bug looks frightening but it actually a shy insect that avoids human contact. But I learned that wheel bugs shouldn’t be handled. If they’re disturbed, they can cause a painful bite (actually, more of a puncture). These “bites” are described as worse than a hornet sting and they can take weeks or even months to heal!
I’m not one who picks up insects – I like looking at them but not handling them. After learning about the wheel bug, I’m glad I’m not an insect handler or I’d probably be writing about my wheel bug bite right now!
Having seen a wheel bug, I’ll never forget what it is. But when I see one from now on, I’ll be glad that it’s there, knowing that it’s been feeding on other insects all season long. Oh, and I’ll be sure to leave it alone!