California Root Borer

Subject: What is this?
Location: Roseville ca
May 16, 2016 6:42 am
I found this in the hallway this morning. It didn’t move at all when I passed by and was easy to catch with Tupperware container. It’s body is about an inch long.
Signature: Debbie

California Root Borer
California Root Borer

Dear Debbie,
This is a male California Root Borer,
Prionus californicus, which you can verify by comparing your individual to this image on BugGuide.  We thought this May sighting was a bit early and unusual, but BugGuide includes data on sightings in California as early as April.  According to BugGuide:  “Adults active summer through early fall; fly at dusk or in the evening” and “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).”

Thank you Mr. Marlos –
We do, in fact, have an apple tree and many oak trees in the field behind our home.  My boys were cutting wood yesterday.  I’ll bet it hitched a ride in with one of them or the dog.
The apple is dying a slow, mysterious death.  Could this critter’s activity be part of the problem?  Don’t worry, I won’t use pesticides.
-Debbie Mulligan

They don’t normally attack healthy trees, but they will attack a compromised tree. The drought has been tough on trees.

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