Flipping rocks in southern Illinois revealed this cool creature. Adults are about one inch long, oblong, flattened, and dark in color with deeply grooved wing covers. There are a dozen or more common species of beetles in the genus, but all others are considerably smaller than this one.
Murky Ground Beetles are active insects, with long legs, large eyes, and strong sickle-like mandibles. They run rapidly and are active mostly at night.
These are regarded as very beneficial to agriculture. Adults feed on the larvae of Colorado Potato Beetle and other harmful larvae, ragweed seeds, and occasionally fruit (probably in search of needed water). They are often attracted to electric lights. Their larvae are wormlike in appearance with powerful prominent jaws.
The Murky Ground Beetle is distributed across North America and found in a wide range of habitats including grasslands, open meadows, forests, agricultural fields, and even in urban areas. Like many Ground Beetles, it can release pungent odor when threatened.