I only see a book louse there. No grain mites from what I can tell. Booklice are completely harmless, and probably beneficial.
In answer to your other question, Monomorium ergatogyna(any Monomorium in CA really) is a native species. They are considered a pest because they will commonly enter houses in search of food. Much better than argentines though in my opinion, they really seem to give native fauna a break by offering some real competition to argentines.
Edited by NickAnter, April 12 2021 - 6:48 PM.
Hi there! I went on a 6 month or so hiatus, in part due, and in part cause of the death of my colonies.
However, I went back to the Sierras, and restarted my collection, which is now as follows:
Aphaenogaster uinta, Camponotus vicinus, Camponotus modoc, Formica cf. aserva, Formica cf. micropthalma, Formica cf. manni, Formica subpolita, Formica cf. subaenescens, Lasius americanus, Manica invidia, Pogonomyrmex salinus, Pogonomyrmex sp. 1, Solenopsis validiuscula, & Solenopsis sp. 3 (new Sierra variant).