Allthefloofs
Songster
That's them! I just checked my boxes and I don't have any infestations anymore. It all started declining with microwaving, really. I'm sure the more frequent changes helped too.Grain mites.....have had them in chicken feed.
Pics, and story here, might help with ID for @jak2002003 :
https://www.backyardchickens.com/threads/grain-mites.981212/