The invention relates to an improved composition for the control of parasites on animals, comprising comparably high amounts of active substances from the group of agonists of the nicotinergic acetylcholine receptors of insects (neonicotinoids) and from pyrethroids in a new and improved formulation comprising carvacrol as a solvent, and optionally additionally further active and/or auxiliary substances. In particular, the invention relates to the use of such compositions for the control of ectoparasites such as, in particular, fleas, ticks and sand flies in pets such as, in particular, in dogs and ferrets.