Entomology (Study of Bugs)/What is this bug?


QUESTION: I found these little bugs in a glue trap that I set for mice.

They are curled up so I had trouble counting the legs. They're tiny... about 3mm body length.

Can you tell me what kind of bug this is and whether I need to be worried about it?


ANSWER: Hi, Kiri:

Thanks for including the image with your question.  These are spider beetles in the genus Gibbium or Mezium .  Here's more:



I would look for the infested item(s), if you can find them, and discard the product(s).  I am unaware of any health threats that these insects pose.  They are mostly a nuisance.


---------- FOLLOW-UP ----------

QUESTION: Thank you! That's exactly what they are.

One follow-up, in case you happen to know: I placed three traps around my apartment. One in the kitchen on the floor, one under a rolling kitchen cabinet where I store crackers/snack foods, and one near the front door a distance from the kitchen where the food is stored.

I left the traps unattended for 2 weeks. When I checked them, I found: 2 beetles in the kitchen trap, 2 in the trap below the cabinet, and 7 in the trap near the door (where there is no food). In addition, they were all on the same side of the trap, indicating to me that they are coming in through the gap under the door.

How likely is it that they are being attracted by the sweet smell of the traps themselves? I could find no evidence of them in my pantry cabinets, and since discovering the mouse a while back, I keep everything meticulously clean. I'm wondering if the smell of traps is drawing them in from wherever they are living.



I don't know that much about these beetles myself, which is why I included the links.  They seem to be a bit mysterious in that it is frequently the case where no real source of "infestation" is ever found.  Since they pose no real health threat, and the damage they do is fairly limited, I wouldn't worry too much.

I know we had a colony of these at the Cincinnati Zoo insectarium when I worked there, and they did very well in an old bag of flour....


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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 AllExperts.com, 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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