Methods and formulations for treating animal ectoparasites, effective against parasites such as fleas and ticks are provided. The methods comprise topically co-administering a non-mobile insect growth regulator, a mobile insect growth regulator, and an adulticide to the animal. Parasiticidal formulations for treating animal ectoparasites are also provided, which can be safe to use and avoids the many common deleterious side effects of conventional topical formulations. The topical formulations comprise a combination of two insect growth regulators and an additional insecticide. The topical formulation can be packaged together or packaged so that active components are stored separately prior to administering the topical insecticide formulation to the animal.