The present invention provides compounds of the formula: (I) wherein: X is O or S； Q1 and Q2 are independently CR5 or N, provided at least one of Q1 and Q2 is N； Y is a direct bond or CH2； R1 is H, optionally substituted alkyl, alkenyl, alkynyl, cycloalkylalkyl, benzyl or oxetan-3-yl-CH2—；； R2 is optionally substituted phenyl, pyridine, pyrimidine, pyrazine or pyridazine； R3 is alkyl or haloalkyl； R4 is optionally substituted pyridine, pyrimidine, pyrazine or pyridazine； R5 is H, alkyl, haloalkyl, cycloalkyl, alkoxy, alkoxyC(O)—； or (alkoxy) 2CH—；； or a salt thereof. The compounds are useful for controlling ectoparasites on animals.
