BIFEN I/T KILLER 4 OZ by BIFEN I/T MfrPartNo 82004429 Bifenthrin 7.9% Bifen IT is a 7.9% bifenthrin insecticide that kills and controls over 75 different pests. It is the most common professional insecticide in use today. Bifenthrin is very safe to use and does not have an odor or leave a visible residue when applied. The Bifen mix ratio varies from .2 ounces to 2 ounces per gallon of water depending on application site and target pest.