Zodiac Spot On flea and tick control for dogs is a long-lasting, once-a-month topical that prevents flea eggs from developing into adult fleas for up to 30 days. Zodiac Spot On also kills and repels ticks and mosquitoes for up to 30 days. Contains 45% etofenprox and 3% s-methoprene, an insect growth regulator. For dogs and puppies 6 months of age or older. Apply 1 tube divided on back between shoulder blades and at base of tail. Do not reapply for 30 days. Do not use on cats.