Go to the sialis web site. They have info on mites. That diotomaceous earth is totally non toxic. Nevermind here it is.
Mites are uncommon in bluebird nests, but are common in Tree Swallows (TRES) nests. Providing TRES with clean feathers for nesting can prevent mite infestations. This is probably unrealistic for large trails. In that case, try replacing the nest; or use a low-level (0.03 - 0.1%) of pyrethrin pesticide, under the nest (as a toxin, this is considered a last resort.) 1/4 teaspoon of all natural food grade (not swimming pool) diatomaceous earth underneath the nest might help - it dries mites out. Put it in a plastic bottle with a very small opening so you can squeeze it out - it comes out in a cloud of dust. If there are nestlings that are too young to move, place your hand or a paper towel over them during dusting.
Cathy

Thanks for the info! We'll keep this in mind for next year. We've heard FCs return to the same nesting place in the following years, fingers crossed. We'd love to have them back - just not their mites... (still scratching here).

Sevin will work.
As a precaution, I always wear surgical gloves when I know I'm going to be checking Tree Swallow boxes.
I learned the hard way.
I read somewhere that a severe infestation can cause fatalities.
Good luck.
dr