Field & Stream Dual Action Flea and Tick Treatment for X-Large Dogs & Puppies 61-150lbs Kills fleas, brown dog ticks, deer ticks, flea eggs and flea larvae. Kills and repels mosquitos. Prevents re-infestations for 1 month. For dogs and puppies 12 weeks and older weighing 61-150 pounds. Convenient drops are easy to apply and designed to provide the protection outdoor dogs need.