How do drain flies get past the P trap? How much DF5000 does it take to get past the P trap and into the line?
The drain flies are not coming up from the P-trap. They are traveling inside from outdoors and reproducing in the organic matter that builds up on the walls inside the drain. You should use 4oz of DF5000 drain fly gel in each drain in the infested room every night for a week. We also have a drain fly kit that comes with DF5000, glue boards to monitor the infestation and an aerosol to knock down the flying adult drain flies.
Answer last updated on: 07/30/2010