American Oil Beetles are black with either a satin, smooth, or matte sheen on their elytra. A blue hue may cover the beetle in certain lighting. The elytra that cover the wings may be shorter than the abdomen of the beetle, leaving the body exposed. What makes these seemingly non-descript beetles unique is their ability to secrete a yellowish oil that reacts painfully with skin and other insects' exoskeletons. This chemical defense occurs when it is threatened or squeezed upon being picked up. The oil can 'burn' a would-be predator to the point of being left along, but it can also cause redness, irritation, and blisters on humans that touch or hold it.
These beetles are most often seen walking through the grass or on patios and sidewalks. They do not fly. They are more active in spring than other times of year, and small children may be attracted to them and try to pick them up, which could elicit the oil secretion.
The American Oil Beetle is typically 0.2 inches to 0.6 inches (7mm to 17mm) in size and has the following descriptors / identifiers: black; blue; hard shell; segmented body; large abdomen; antenna.
Territorial Area Map (Visual Reference Guide)
The map below showcases (in blue) the states and territories of North America where the American Oil Beetle may be found (but is not limited to). This sort of data can be useful in seeing concentrations of a particular species over the continent as well as revealing possible migratory patterns over a species' given lifespan. Some species are naturally confined by environment, weather, mating habits, food resources and the like while others see widespread expansion across most, or all, of North America.