Unknown Longicorn from California is Acanthocinus principes

Some kind of longhorn beetle?
July 18, 2009
This insect had apparently been attracted to the yard light at the corner of our house. It’s July, in a woodsy area of the Sierra Foothills near Placerville, California. (Lots of ponderosa pine and black oaks, as well as manzanita shrubs.) In my I.D. search I keep coming across the Banded Alder Borer but this is something else. Can you help?
Karen Rathbun
Placerville, California

Unknown Longicorn from California
Acanthocinus principes

Hi Karen,
You are correct that this is not a Banded Alder Borer, but we have had no luck in securing an identification for you.  We are nearly certain your beetle is in the subfamily Lamiinae which includes the genus Monochamus.  We would seriously consider the White Spotted Sawyer, but the male of the subspecies found in California and Oregon has solid black antenna.  We are going to contact Eric Eaton in the hopes that he can assist in an identification.

Unknown Longicorn from California
Acanthocinus principes

Comment from Eric Eaton
I recognize it, but never committed the name to memory because it is not seen that often.  I’ll get more of my colleagues to take a look. Nice images that I hope will also get posted to Bugguide:-)

Okay, I’ve submitted it to BugGuide, and also added one more photo. I’m excited that this one is not common, and now I wish I had not been rushed when taking the photos and had done a proper job of it — including a size reference and finding better lighting and that sort of thing. Or that I had saved the beetle for a proper photo session later. Thanks for your help!

July 19,2009
Daniel, thanks for your help! I thought you would like to know that Eric has identified this beetle as Acanthocinus principes  —  http://bugguide.net/node/view/306477/tree
What fun to be able to provide photos that seem somewhat hard to come by!  I just got lucky, as I know next to nothing about insects, though I do own a couple of field guides and like to learn the names of things that I find.  I sure appreciate your service, and also Eric’s.

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