Virbac Knockout Area Treatment kills adult fleas and ticks and controls pre-adult fleas (larvae) for 120 days. It contains a unique combination of ingredients that kills both adult and pre-adult fleas, and even kills fleas before they grow up to bite. Nylar, a unique ingredient in this flea spray, continues to kill fleas for 120 days (4 months) by preventing their development into the adult biting stage. It reaches fleas hidden in carpets, rugs, drapes, upholstery, pet bedding, and floor cracks. Protects your home from reinfestation and flea buildup. Protects your pets and family from bites. One treatment with this spray gives continuous flea protection for 120 days. Leaves no objectionable odor or sticky mess and, used as directed, does not stain furnishings.