Wayne from Perry, Ga writes,
How do you apply for drain flys when you are unsure which drain they are coming from?
We recommend you use the Gentrol Aerosol for drain fly infestations. For drains, apply product into and around the downspout and catch basin area. Coat these areas thoroughly as fly larva develop in the scum buildup on the sides of drain pipes. Repeat applications at 2 to 4 week intervals depending upon the severity of infestation. You can treat all of the drains in the infested areas.
Answer last updated on: 07/29/2012