The present invention provides an animal ectoparasite-controlling agent containing as an active ingredient a hydrazide compound represented by the formula (1)wherein R3 represents a fluorine atom, a chlorine atom, a bromine atom, a methyl group, an ethyl group or a hydrogen atom, R5 and R6 are the same or different each other and each represents a methyl group or a hydrogen atom, R4 represents a C1-C6 alkyl group substituted by a C1-C6 alkoxy group, which shows excellent controlling effects on animal ectoparasites.本發明提供一種動物外部寄生生物防治劑,係含有下述式(1)表示的醯肼化合物為活性成分:式中R3表示氟原子、氯原子、溴原子、甲基、乙基或氫原子;R5與R6可以是相同或不相同,各分別表示甲基或氫原子;以及R4表示經C1-C6烷氧基取代之C1-C6烷基,該防治劑對動物外部寄生生物表現優異的防治效果。本案無圖式。
