Insects and Spiders - native

California Prionus Beetle (Prionus californicus) on Jul 29, 2025

Originally reported as Ponderous Borer (Trichocnemis spiculatus)

Submitter has sample

Description of specimen

Large brown beetle

Commentary

Thank you for your report! This is actually California prionus rather than Ponderous borer, but they are closely related and have similar lifestyles: they are not pests and you can let it go. These beetles are natives that breed in decaying conifer stumps and logs. They rarely attack the roots of living trees.

Tom Valente
July 30, 2025, 4:54 a.m.