What it looks like: 3-4 mm in length. Its body is dark brown with striae, or shallow punctures, running the length of its elytra. The rows of striae alternate with rows of light brown, short hairs.

Where you'll find it: This beetle is found throughout the coastal California mountain ranges, in large, clear, rapid streams.

Natural History: These beetles are abundant where bars of coarse gravel drop off into deep pools. Both the adults and the larvae are aquatic.