Insects and Spiders - native

Ponderous Borer (Trichocnemis spiculatus) on Sep 7, 2022

Originally reported as Longhorn Beetles (Cerambycidae)

Submitter does not have a specimen

Description of specimen

3-4 inches long. Dark Brown/Black. I think it's a female California Prionus Root Borer Beetle. Stayed on plant for 4 hours 9/6/2022. Saw it at 3:00 pm.


No need to do anything! Here's the identification:
Order: Coleoptera
Family: Cerambycidae
Species: Trichocnemis spiculatus

This is Trichocnemis spiculatus, the ponderous borer. Their larvae feed in stressed, dead, and decaying conifers of all sorts; the adults don't feed. They are native to Oregon and they are the largest beetle in the West. They are often attracted to homes due to lights. No danger!

Josh Vlach
Sept. 8, 2022, 8:09 a.m.