Soil mites - hard to identify - please help!
I recently noticed that I have some sort of bug infestation that looks like a mite (it is very tiny but I can see it if I look very closely) in the soil of several of my houseplants. I have re-potted (washed off all soil on the roots) all but one that had known "mites." I have not found any of these tiny bugs on any of the leaves of my various plants (I have nearly 100 houseplants). I am very worried about these spreading and causing harm. Isolating the plants also isn't that practical--I only have a few areas of adequate light. There may be two different types as well--at first they looked like teeny-tiny silvery/white beetle shaped bugs but the ones I've seen lately look more white/tan colored and more like mites. They do not jump, there are no webs, and there aren't that many signs of plant trouble expect for a few plants that aren't thriving (which there are definitely other explanations for). I also believe I have fungus gnats, but these "mites" are not the larval form. Because of the cold winter weather where I live, I don't think I can take the plants outdoors to spray (unless it was only for a few minutes). I have used a neem oil spray (ferti-lome Triple Action plus RTU), but I don't think that will actually kill them nor penetrate the soil adequately. Any help would be greatly appreciated--I don't want to throw away 100 plants!!!