Cucujus clavipes is the largest flat bark beetle (Family Cucujidae) in North America. This may not seem like much since most other species in the family (and related groups) are normally not much more than a quarter of an inch long. Cucujus clavipes, by contrast, commonly comes in at over half an inch. It is also striking in its bright reddish color.
It lives under the bark of dead trees and feeds on other insects. I have seen it in a number of US states (north, south, east and west) but it seems to be most abundant in the coniferous forests of the Western US. This individual was found about 40 miles northeast of Fresno (California) under the bark of fallen Douglas fir at about 6,000 feet.