I live in a 2 year old walkout ranch in the midwest. Just recently i've noticed millipedes and other bugs coming from the drain in the tub. We have a septic tank and i've also noticed that when i open the cap to clean the filter every 2-3 weeks, there seems to be alot of flies in there. Is this related to the drain bugs? How can i get rid of this problem? I dont want to bathe my kids in that tub. It hasn't affected any other drains. Please help.