Hartz Ultra Guard Plus Drops for Cats 5lbs. & Over. For use on cats 5 lbs and over. Kills: fleas, deet ticks, flea eggs for up to 1 month. Kills & repels: mosquitoes. 3 month supply. Prevents re-infestation for up to 30 days. Kills mosquitoes that may transmit heartworm disease. Kills fleas that may cause flea allergy dermatitis, flea bite anemia and tapeworm infestation. This product contains 3 monthly dosages, each 1.8 ml.