Liberty 50Plus IGR Spot On For  Large Dog  600556 For dogs 33 to 66 lbs For use on small dogs over 12 weeks of age Kills 5 different kinds of pests on dogs including fleas, ticks, mosquitoes, lice, and mites Kills, repels, and prevents reinfestation of fleas for up to 5 weeks Kills flea eggs and larvae for up to 8 weeks