These Assassin Bugs have Wheels on their Backs.

We’ve seen a lot of these relatively large bugs lately. This is a wheelbug, arilus cristatus. Members of the assassin bug family, they have a huge proboscis that folds into a special groove on their bodies.  They use this formidable tool to paralyze and then consume prey.  They also have a sort of wheel (see how the structure on their back looks like the cogs of a wheel?) that gives them their name.

During the Christmas bird count, one of these wheelbugs landed upside down right in the road in front of us, and I think it was dropped by a bird.  We used a twig to scoop it out of the road.  Adults are grayish and can be over an inch long. 


Young wheelbugs (nymphs) look totally different.

Young wheelbugs are orange or red with dots, and they haven’t developed that characteristic wheel yet.  These little guys look like cartoon bugs, and it’s hard to imagine that they grow over several morphs to eventually become the gray adult with the big wheel.



They prey on caterpillars like tobacco hornworms, which can be the bane of gardeners, so they are considered “beneficial insects”.  We didn’t pick any up, because supposedly that proboscis can deliver a nasty bite!  They eat by inserting that probiscis into the fleshy part of an insect (above, a swallowtail butterfly caterpillar, photo by Dr. Merle Shepard).  They can ingest the fluids of that insect like drinking through a straw.  There’s some great information over here at the University of Florida’s entymology site.