Mold, Grain, or Storage Mite.
Still fighting them in our Tree Frogs cage. We are waiting for our shipment of new substrate, coconut fiber ( which is probably how we got these things! Kopra Itch is something ppl get when they work with these coconuts) These mites are more hardy than some! We've dried it out, which did lessen the numbers we were seeing but didn't eradicate them. The temps were pretty cold for weeks and they were just fine. We saw a few less a day but they were still active.
We aren't seeing large numbers as I've seen other ppl dealing with, however when I'm seeing up to 6-10 on the glass of the aquarium during the day.. ik there's probably 100x's more in the substrate I'm not seeing at all.. not to mention the nymphs and juveniles that are almost impossible to see with the naked eye!
I can't believe I can see the adults with my naked eye. they are way smaller than a grain of salt, sugar, etc.. they literally look like a tan/white speck of dust. But see them I can and it grosses me out!
So I share it with you.
We've tried Vaseline at the top of the cage, double sided sticky tape and they can and do crawl right on top of both without getting caught. I watched it with my own eyes and had to kill the ones I watched and experimented with. I've also seen them crawl over a 2in line of bug spray that was still tacky and only partially dried. I know 1 of them eventually died but I'm not sure if all of them or even some of them died afterwards. I wiped up and disposed of the ones I watched.