Natural History

One of the most commonly encountered desert insects, stinkbugs are active year round. During the summer they are most active at twilight and early sunrise (crepuscular) or night (nocturnal). In the fall & winter, they revert to a more diurnal lifestyle. Pinacate beetles are often seen as they walk around in the desert, seemingly wandering at random. Studies have shown that they are probably in search of food, which they find by odor. They primarily eat detritus of grasses and forbs (forbs are the plants that often bloom with wild flowers).
 

They are well known for their comical, yet effective, defense tactics. When alarmed they stand on their heads by bending their front legs down and extending their rear legs. Depending upon the species, they exude an oily, smelly secretion, which collects at the tip of the abdomen or spreads over posterior parts of the body, or they eject the reddish brown to brown secretion as a spray. Larger desert species can spray 10 to 20 inches. Most species can spray multiple times, if necessary. The spray is not painful unless you get it in your eyes or mouth, where it may cause burning and temporarily blinding.