What is this beetle
I hate to even bother you. Tonight when carrying in the groceries, I had twenty of these come in with me. They are all over the sidewalks and the dirt road in front of the house. My cats were going crazy chasing them. I believe they may be Giant Root Borer, but my daughter whom I home school is not at all sure it matches your pictures. She has taken several nice pictures could you please, if you have the time, verify if this is a root borer or perhaps one you have listed as the mystery beetle. Thank you for your time
Jo and Vicki Petit
Elbert, Colorado
July 2, 2008

Hi Jo and Vicki,
Your beetle is definitely a Prionid Root Borer, and we believe it is the Tile-Horned Prionus, Prionus imbricornis. We will contact Eric Eaton for verification. The hairiness of the thorax is curious. Were the images photoshopped to create the white background? If so, some valuable details like antennae segments might be missing. Your account of the beetle encounter at the grocery store will probably chill some of our readers. Prionid Beetles actually have very strong jaws and can produce a painful, though harmless bite.

Hi Daniel,
No photoshop, it had flown into a white box and my daughter used her kodak digital camera on Macro lens, that was straight out of the camera but cropped down to just the beetle, but nothing more than cropping was done. These came in the house while we were carrying in Groceries (not at the grocery store). They were all over my yard and the road in front my house which is a dirt road and about 20 that came in the house, I am guessing because of the light. They are all about an inch and half to two inches long (the body and twice that with the antennas and legs.) Thank you for your help, Vicki will be very excited that you have answered us, we appreciate your time

Update: (07/03/2008)
Like you, I am puzzled by the hairy thorax. … There is another genus of prionid (Tragosoma) with a hairy thorax and elytra with similar texture; antennae of Tragosoma are NOT like Prionus. Just to be sure, I will invite Bugguide folks and Entomo-l folks to take a look. Stay tuned.

Identification: Prionus emarginatus
Hi Eric,
That bug is Prionus emarginatus

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