Washington has numerous beetles belonging to several families like scarab, and longhorn beetles, distributed in the eastern and western parts. Eastern Washington houses species like the mountain pine beetle, a significant threat to the forests, alongcol3 Northern Carrion beetle, American oil beetle, etc.
The ten-lined June beetle measuring up to 28 mm found between June and July mainly occurs in the southeastern parts of the state. The big-sized Japanese beetle is not a native here but can be found in some parts infesting plants. Another annoying pest here is the blister beetles found in alfalfa plants, which are harmful to horses.
Largest Beetles: Ten-lined June Beetle, Japanese Beetle, California Prionus Beetle