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Entomology (Study of Bugs)/unfamiliar bugs mass from compost bin


escaping compost bin bugs
escaping compost bin b  
This afternoon scores or hundreds of these strange bugs crawled across the patio on which our apartment building's compost bin sits. (Oakland, California)

The Bin is the size of a large plastic municipal garbage can and has wheels, i.e., it's kind of massive.

These weird caterpillar-looking but not hairy critters slower moved across the patio. Lifting the compost bin's lid revealed hundreds of these crawling up the inner walls and on the rim.

I ruled out fly maggots after seeing maggot photos online. I haven't been able to find this bug in descriptions.

Hi, John,

Thank you for including the image with your question, but I knew immediately what you were talking about even before I saw the picture.

They actually *are* maggots, those of the Black Soldier Fly, Hermetia illucens .  More about them here:

Apparently, they are a very *good* thing to have in your compost bin:

Thanks for sharing your findings!


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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