California Root Borer

Subject: Roach or Beetle?
Location: Blackfoot, Idaho
July 22, 2016 8:37 am
We live in southeastern Idaho and have for almost 40 years and we have never seen anything like this. We found one in our garage last week (Mid-July) and another one last night in our garage as well. It is a little over 2″ long and makes a clicking-hiss sound when disturbed. Initially we thought it was a cockroach and panicked at the thought of a cockroach invasion, but after doing some research, we think it is a beetle of some kind. Based on photos we have seen, it looks similar to the Palo Verde Borer. What do you think it is? And will it cause any damage to our home, trees, etc.? We took several photos but it was on the move so most of them were blurry. Thank you for your help!
Signature: Christine

California Root Borer
California Root Borer

Dear Christine,
You are correct that this is NOT a Cockroach, and though it is not a Palo Verde Root Borer, it is a member of the same subfamily Prioninae.  This is a California Root Borer,
Prionus californicus,  though that name is somewhat deceptive as the range includes much of western North America and is not limited to California.  According to BugGuide:  “Larva feed primarily on living deciduous trees (oaks, madrone, cottonwood) and are also recorded from roots of vines, grasses, and decomposing hardwoods and conifers. Will also attack fruit trees growing on light, well-drained soils (e.g. apple, cherry, peach).”  In our opinion, there is rarely enough of an infestation to damage healthy trees.

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