About Promecognathus laevissimus (Dejean, 1829)
Promecognathus laevissimus, commonly called the smooth millipede hunter, is a species of ground beetle that belongs to the family Carabidae. This species is found in western North America, specifically in the US states of Oregon, California, and Nevada. It is a close relative of Promecognathus crassus. Just like P. crassus, P. laevissimus uses its large jaws to hunt and feed on millipedes. This includes millipede species that produce hydrogen cyanide and benzaldehyde as defensive toxins, such as Xystocheir dissecta. P. laevissimus has a high tolerance to these defensive toxins. Adult smooth millipede hunters are glossy black beetles, ranging from 5 to 18 millimetres (0.20 to 0.71 inches) in length. They have long jaws and a narrow thorax, and are active at night.
