Advantix (grey) for large dogs is a topical treatment which treats and prevents flea infestation, and kills and repels ticks, biting lice, mosquitos and sand flies. Applied once a month to the back of your dog's neck, it starts killing fleas and larvae immediately upon application. It helps to reduce the level of infestation in the treated dogs environment, and prevents reinfestations of new adult fleas for up to one month after treatment. Advantix provides effective control by repelling and killing mosquitoes before they attack, and also stops ticks and fleas from pesky biting. It kills and repels brown dog ticks for up to four weeks, paralysis ticks for up to two weeks, and mosquitos, sand flies and lice for up to six weeks. Advantix is water resistant; it keeps working after bathing, shampooing and swimming. Please note this product is for use on dogs and puppies over the age of seven weeks, and is not suitable at all for cats and kittens. Use only as direct ed on the label.