Disclosed is a method of controlling ectoparasites that infest companion andlivestock animals by applying to the animal an effective amount of 4-tert-butylphenethylquinazolin-4-yl ether or 4-chloro-5-ethyl-2-methyl-N-[(4-tert-butylphenyl)methyl]pyrazole-3-carboxamideor 5-chloro-N-[2-[4-(2-ethoxyethyl)-2,3-dimethylphenoxy]ethyl]-6-ethyl-4-pyrimidinamineor 4-chloro-3-ethyl-1-methyl -N-[4-(p-tolyloxy)benzyl]pyrazole-5-carboxamide.
