The Blue Fungus Beetle Cypherotylus californicus is a striking species in the pleasing fungus beetle family Erotylidae, notable for its jewel-toned elytra—the hardened wings—studded with black dots that naturally fade to gray with age. Adults measure approximately 1.4–1.8 cm (0.6–0.7 in) long. The head, underside, legs, and eyes are typically glossy black, creating a vivid contrast with the body’s blue sheen.
This species is found across western North America—from Wyoming, Colorado, New Mexico, Arizona, California, and Kansas down into Sonora, Mexico. It favors moist forest ecosystems—particularly areas with decaying logs covered in bracket fungi, where both adults and larvae feed.
Larvae hatch in spring and develop within bracket fungi on dead wood, consuming fungal tissue as they grow. When ready, larvae gather in clusters on the underside of logs, hanging in groups reminiscent of miniature bat roosts as they pupate. Adults emerge in summer, feeding on both fungi and pollen or nectar. They may overwinter as adults and lay eggs the following spring, starting the cycle anew.
As both larvae and adults feed on fungi, the Blue Fungus Beetle plays an important role in the decomposition of woody debris, helping cycle nutrients back into forest soil and maintaining habitat dynamics for countless organisms. Its presence signals healthy fungal communities and robust decay processes—making it a valuable indicator species of forest ecosystem health.