Longhorned Borer: Semanotus amethystinum we believe

Subject: shiny blue beetle
Location: portland oregon
June 26, 2012 5:15 pm
I am a preschool teacher in Portland Oregon. I found some of the kids on the playground playing with this beetle a few weeks ago. we kept it for a few days in a small aquarium with some of the plants we had found it around. since we let it go we have found several more of these around the playground some of them dead or injured. we would like to know what kind of beetle they are and what they eat so if we find ones that are injured the children can try to keep and take care of them.
Signature: sara s.

Longhorned Borer Beetle

Hi Sara,
This is one of the Longhorned Borer Beetles in the family Cerambycidae, however, we were not familiar with this beauty.  We quickly found what we believe is a correct identification as
Semanotus amythstinum on BugGuide.  We want to get a second opinion from Eric Eaton.  If we are correct, the host tree is Incense Cedar.   If we are correct, there are not many photos online and very little information on the species.  The host plant would provide the larval food source and we are not certain what the adults eat.

Eric Eaton confirms identification.
Yes it is!  One of my favorite beetles from there 🙂
When it comes to wood-boring beetles, timing is everything.  If you are not in the right place at the right time, you would never know such animals even existed.  They tend to be locally-common, too, because as larvae they develop only in wood of a certain age and condition.  So yes, they are uncommon unless you know where and when to look.

I can see why its one of your favorites. It was the most adorable and sociable bugs I have ever met. When we would take her out of the enclosure she would walk up and down our arms then fly around the kitchen then land back on one of us. She would sometimes crawl right to the edge of my husbands hand and seem to look him right in the face almost like she was communicating.
I have a strange question. Does it spin silk. I ask because it was hanging from its ovipositor and a strange sticky substance was on the side of the aquarium. I made certain there were no other bugs in the enclosure.

To the best of our knowledge, they do not spin silk.

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