The wheel bug looks like a vintage metal friction toy. It's difficult to believe it is a living creature, but easy to believe it could be harmful. My National Audubon Society Field Guide to Insects and Spiders says:
1 1/8-1 3/8" long. Gray-brown to black. Prothorax raised into a curved series of coglike teeth along midline...This handsome predator can give a painful stab when it defends itself from a careless handler...[eats] caterpillars, even the larger ones including hornworms...
|Connemara Conservancy 6/22/2014|
I spotted a wheel bug on a soggy walk at the Connemara Nature Conservancy this rainy morning. Tried to photograph it with my camera inside a ziplock bag without great success. Once you have seen a wheel bug, you are unlikely to forget its identification.