What's That Beetle?: Unknown Metallic Green and Orange Beetle from Pacific Northwest is Pseudogaurotina cressoni

Beautiful metallic green and orange beetle
Location:  Southern Central Washington State, 2000 ft. elevation.
August 3, 2010 8:17 pm
Dear bugman,
My boys and I found this lovely beetle crawling across our deck this June. It’s a beautiful metallic, almost iridesent dark green with bright orange on it’s legs and abdomen. I placed a ruler next to it for an idea of it’s size.
I did some research and found that it might be a ”Ground Beetle” known as a Caterpillar Hunter, but none of the examples I found displays the bright orange this one does.
Just wondering if you know.
Thanks so much!
Curious Mom

Dear Curious Mom,
This is one of the greatest challenges we have faced in a long long time.  First, this beetle is positively gorgeous and we are not certain where to begin to try to identify it, but we do not believe it is a Caterpillar Hunter.  Challenges like this make us lament that we do not have a strong science background.  We have to approach this from the eyes of artists who are generally not as structured as scientists.  Our gut instinct is that is must be a Longhorned Borer Beetle in the family Cerambycidae based on the antennae, including their position on the head, but we question that taxonomy.  We are going to post your letter as unidentified and it will be prominently featured on our homepage until we get an identification.  We will also elicit the assistance of Eric Eaton who we suspect will be able to nail a proper identification lickety split.

We want to compliment you on the excellent photographs that should assist in the identification process.  The ruler for scale indicates that this is a large beetle, which makes it all the more confusing that we cannot recall ever seeing anything remotely similar in appearance.

Eric Eaton responds
Daniel:
Your family ID is totally correct:  Cerambycidae.  Looks to me like a species of Gaurotes, but I don’t know which ones occur there in the Pacific Northwest.  I sold my reference to the beetles of that region, and my books on U.S. beetles in general are on loan to a friend.
Eric
Oooh, have the person send the images over to Bugguide.  That way one of our longhorned beetle experts can address it.  Might well be a new species for the guide.  Thanks.
Eric

Update
One of our readers who frequently assists with difficult beetle identifications, mardikavana, has confirmed our original suspicion that this beauty is a Longhorned Borer Beetle in the family Cerambycidae, more specifically Pseudogaurotina cressoni.  BugGuide does have a page on this species, but there is not much information on it.  The Insects of Alberta website indicates that it is found in June and it feeds on pollen.

Thank you so much! My boys were thrilled to find out that it is a pollen eater, they weren’t too fond of the idea of it out there eating caterpillars. They loved seeing the pics posted on the site too and I am happy to know what it is. We have a variety of the longhorn beetles around here, but I have never seen one as beautiful as this one.
Thanks again for the wonderful educational service you provide! Your information on house centipedes kept me from having a small heart attack when I found several of them on my deck 🙂
Curious Mom

Hi Again Curious Mom,
We heard back from Eric Eaton who has requested that you also submit your photo to BugGuide.

I would be glad to.

Another Update from Eric Eaton
August 5, 2010
Daniel:
I’m really not sure, but the main way I usually tell the two apart is that Gaurotes has smooth, shiny elytra (wing covers), whereas Pseudogaurotina has textured elytra that are consequently slightly duller in color.  Bugguide experts on Cerambycidae should know more.
Eric