Disclosed is a method of controlling ectoparasites that infest companion and livestock animals by applying to the animal an effective amount of 4-tert-butylphenethyl quinazolin-4-yl either or 4-chloro-5-ethyl-2-methyl-N-[(4-tert-butylphenyl)methyl]pyrazole-3-carboxamide or 5-chloro-N-[2-[4(2-ethoxyethyl)-2,3-dimethylphenoxy]ethyl]-6-ethyl-4-pyrimidinamine.
