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Entomology (Study of Bugs)/Large insect in Oregon coastal home


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Location is Coos Bay Oregon. I've found two of these insects in my house in the past week, both having been discovered at night time after the sun has gone down. Dates being in June 16th and June 20th. The insect is quite large. The head and legs of it are black while the long wings go from a dark brown to a lighter brown. The insect were both found in window sills. Both insects looked identical. Both crawled, and attempt to fly but don't seem to make it very far, and when disturbed appear to make an audible hissing noise. Interested in finding out what type of bug this is and if I might have an infestation on my hands.

Thank you for your time,


I am so-o-o jealous!  I lived in Oregon for the first 27 years of my life and not once did I see a live example of one of these beetles!  This is easily the largest insect you can find in the Pacific Northwest.

It is known as the "Ponderous Borer," Trichocnemis spiculatus (formerly Ergates spiculatus ).  Here's more:

They are sometimes attracted to lights at night, so don't be surprised if a few more turn up.


Entomology (Study of Bugs)

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Eric R. Eaton


I answer insect and spider identification questions ONLY. Attach images if possible. No "what bit me?", "what do I feed this bug in captivity?", or science fair project questions please. NO TECHNICAL QUESTIONS ABOUT INSECT PHYSIOLOGY.


Principal author, Kaufman Field Guide to Insects of North America. Professional entomologist employed previously at University of Massachusetts, Chase Studio, Inc., and Cincinnati Zoo; contract work for West Virginia Department of Natural Resources, Smithsonian Institution, and Portland (Oregon) State University.

Author, Kaufman Field Guide to Insects of North America, Missouri Conservationist magazine, Ranger Rick, Birds & Blooms, Timeline (journal of the Ohio Historical Society). I have contributed to several books as well.

Oregon State University, undergraduate major in entomology, did not receive degree.

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One of the top 50 experts in all categories for, 2009.

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Principal author of the Kaufman Field Guide to Insects of North America, Smithsonian Institution (contract), Cincinnati Zoo (employer), Portland State University (contract), Chase Studio, Inc (employer), Arkansas Museum of Discovery (guest speaker). Currently seeking speaking engagements, leadership roles at nature festivals, workshops, and ecotours.

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