SHERLEYS DEFEST HOME SPRAY 400 ML. Defest 3 Months Household flea spray Environmental flea control is an essential part of keeping your pets free from unwelcome parasites. Defest 3 Months is the product of choice when fleas have already established themselves in your home. Apply to all rooms to which pets have had access. Combine treatment with regular vacuuming and wash all pet bedding. Due to the nature of the flea life-cycle, once fleas have become established, it may take several weeks to completely eradicate them. Read the label carefully before using.