Mortein Do-It-Yourself Professional Outdoor & Indoor Surface Spray is an insecticide, not a repellent — it’s not designed to keep insects off the area you’ve sprayed. Instead, it leaves behind an insecticide residue that the insect absorbs as it comes into contact with the treated area. This residue lasts for up to 3 months outdoors. The product is intended to kill the insect before it breeds, preventing infestation. The extent and severity of the existing problem will determine the length of time before you notice a decrease in insects. Ants are the most difficult to kill with residual spray products. As ants walk across the treated area they pick up a small dose of insecticide, which may not kill them immediately.
