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Pests/Black beetle found in furnace


Black bug
Black bug  
We were having our air ducts cleaned and the technician discovered these black bugs behind the face plate. He says he's never seen any bugs in a furnace before. We thought they were dead because they were moving but then when touched these things moved. We sanitized our whole system now bc we have no idea where they came from. Unfortunately I found one on the floor this morning. Are these dangerous? Should we get an exterminator?


This could be a click beetle (Elateridae) but the image is a bit too fuzzy to be certain. These are not usually found indoors so it is a mystery how they got there. They are harmless and no reason to treat. Your best option is probably to collect a few and take them to your county Cooperative Extension office for identification (or UC Davis/UC Riverside if closer) - check

Jack DeAngelis


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Jack DeAngelis


I can answer questions in any area of entomology (study of insects, spiders, mites, ticks, and other terrestrial arthropods). Contact me about home and garden insects such as aphids and spider mites, insects that bite and sting such as ticks and wasps, and insects that damage homes such as carpenter ants and termites.


20 years as university extension entomologist, now retired; currently publish a website about home and garden insects.


see Fine Gardening magazine

Ph.D. in Entomology (the study of insects)

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