After having a bathroom toilet drain clog cleared by a plumber by using a snake, we have experienced an infestation of drain moths. How may we eliminate the infestation?
They are saying a product like invade bio drain will work https://www.doyourownpestcontrol.com/drainflies.htm
If by drain flies you mean fruit flies I've had flawless success with a shallow bowl of apple cider vinegar with a little Dawn on top. They fly in and can't get out. A few days to clear em out.