Answer: Bifen IT is to give off a residual to last up to 30 days outdoors for the insects that come into contact with the residual left behind. With mosquitoes this will take some time to see any results because they are flying insects. It can take time to see any result after application.Click to see full answer. Simply so, how long does bifenthrin take to work?Bifenthrin is slowly absorbed by the body after being eaten, and most of it is excreted within 3-7 days. Studies indicate that bifenthrin does not absorb through the skin well.Additionally, is Bifen it safe for pets? Synthetic pyrethroid insecticides such as Bifen can be harmful to cats IF applied to them directly such as with a Dip. Bottom line is that it is a very good insecticide for fleas and ticks, and once applied, if allowed to completely dry before allowing the animals back onto it, there should be no problem. Likewise, how long does it take Bifen to dry? Generally, after an application of Bifen IT it should take anywhere between 30 min – 1 hour to dry.How do you use Bifen it?For a 0.06% rate apply 1 gallon of dilution per 10 square feet, or use 1 fluid ounce of Bifen I/T per 10 square feet in sufficient water (no less than ½ gallon or more than 2 gallons) to provide thorough and continuous coverage of the area being treated.