Arilus cristatus or Wheel Bug

Arilus cristatus ‘Wheel Bug’

Pay careful attention to the goings-on in your garden this autumn and you might just catch a glimpse of a large, pre-historic looking bug moseying about searching for a mate. This is a “wheel bug” or more properly, an Arilus cristatus and one of the largest “true bugs” in North America. A member of the assassin bug family, they can get up to 1.5″ in length (as the one seen above) but, despite it’s size, are rarely seen as they are very good at camouflage and are shy insects. A wheel bug lays it’s eggs in autumn in a honeycomb like egg case usually attached to some kind of twig. The eggs will hatch the following spring and the nymphs will go through several stages of growth before reaching adulthood. As a point of fact, I encountered a wheel bug nymph in our garden last summer and had no idea what is was but it was quite fascinating looking. Now I know!

EDIT: 6/’12 Snapped a photo of a wheel bug nymph just the other day…see?

Wheel bugs are actually quite shy, but of course it’s best to keep your distance.

Wheel bugs have a prominent ridging (which look like the cog of a wheel, hence the name), but it’s the long, dagger-like beak which is most noticeable. The wheel bug utilizes this beak to plunge into it’s victims, injecting a venom which paralyzes and dissolves it’s insides so it can feed. Totally creeped out yet? I’m sure I don’t need to tell you that you want to observe this insect at a distance, because if you were to be stung by it, it would hurt more than a bee sting and could take several months to heal. Did I forget to mention the wheel bug can also fly and can eject a stink sac when disturbed? Yes, best to leave this one alone. Wheel bugs are voracious eaters and will, sadly, consume ladybird beetles and honeybees. However they also eat soft-bodied chewing insects (which is a good thing in a situation where there are a lot of trees being preyed upon by moth larvae), aphids and Japanese Beetles. Like praying mantis, which is also a non discriminatory predator, wheel bugs are considered a beneficial insect.