Thank you. The worms had just been fed when I got it. I'll wait and check it again in a week.

A very high population of mites may take weeks or months to moderate its numbers, depending on how much food is already in the bin. Don't worry about them too much in the meantime, but do make sure that you're adding new food very slowly and also adding new bedding material as you go along.

I added dry bedding - shredded paper - then the next day I could hardly find any of the mystery bugs. Previously there were 100's of thousands inside & outside the bin.

I also read that melon rind will attract them. So I put some inside top of bin that night, expecting to find it covered with mites the next morning. There were very few.

So I'm not sure what was going on.

BTW we lived in, and LOVED, the Philly area for over 15 yrs before moving back to the Poconos to be closer to aging parents.

I'm fond of Philly myself. I've only lived here since 2014 but my sister and brother-in-law have been here more than 25 years. It's America's Garden Capital! (tm) (at least according to the visitor's bureau or whoever markets these things.)

Those are mites... the kind that won't harm your worms (or you). It is usually indicative of very wet bin conditions (and often overfed)... let the bin contents dry out some and the mites will also dry out and be gone. Mostly try not to over feed with the high moisture stuff.