Zodiac Dog Powerspot Over 30 lb contains a powerful, effective insecticide which kills adult fleas and ticks on contact. It also kills Blacklegged Ticks (Deer Ticks) which may carry the organism that carries Lyme disease. It kills flea eggs laid on your pet for up to 4 weeks. This topical treatment spreads completely over your pet's body through the natural motion of the animal. Zodiac Powerspot is an effective, easy-to-use, economical product designed to be used once a month. Each package contains a 4 month supply.