Jennifer: I am unfamiliar with sewer/toilet mites, yet do know of drain flies and fungus gnats. Both favor locations with higher levels of humidity such as bathrooms and floor drains. Running a de-humidifier or even a small fan to circulate air in the bathroom can be enough to solve the problem. Both will also live at the air/water line in a floor drain. Pouring 3-5 gallons of water with a detergent or bleach in the drain will flush them along. Additionally using a scrub brush of your choosing, clean the walls of he drain especially at the air water line is also recommended. Lastly about once a month flush out the drain to keep them from establishing. If i am off the mark and you are able to send me images to my email, will lookl at them and reply.
