An object of the invention is to provide a pest control composition that contains a novel active ingredient and is effective in the control of pests, a method for using such a composition, and a novel quinoline-based compound. The invention provides a pest control composition containing, as an active ingredient, at least one component exhibiting pest control activity selected from the group consisting of compounds represented by formula (1) shown below or salts thereof and quinoline-based compounds, and also provides a novel quinoline-based compound which exhibits pest control activity. In the formula, R1 represents an alkyl group of 1 to 6 carbon atoms which may be substituted, or a haloalkyl group of 1 to 6 carbon atoms or the like, R2 represents a halogen atom, an alkyl group of 1 to 6 carbon atoms which may be substituted, or an alkoxy group of 1 to 6 carbon atoms which may be substituted or the like, R3 represents a hydrogen atom, a halogen atom, or an alkyl group of 1 to 6 carbon atoms which may be substituted or the like, n represents an integer from 0 to 5, X represents an oxygen atom or a sulfur atom, Y represents a phenyl group with a substituent at the ortho position, or a pyridyl group or the like, and the bond that includes the dashed line portion represents a double bond or a single bond.本發明提供含有新穎有效成分之對於防除有害生物有用的有害生物防除組成物及其使用方法、及新穎喹啉系化合物。係提供含有下式(1)表示之化合物或其鹽、及選自喹啉系化合物中之1種以上之具有害生物防除活性之成分作為有效成分之有害生物防除組成物、及具有害生物防除活性之新穎喹啉系化合物。 式中,R1表示也可經取代之C1~C6之烷基、C1~C6之鹵烷基等,R2表示鹵素原子、也可經取代之C1~C6之烷基、也可經取代之C1~C6之烷氧基等,R3表示氫原子、鹵素原子、也可經取代之C1~C6之烷基等,n表示0~5之整數,X表示氧原子或硫原子,Y表示在鄰位有取代基之苯基、吡啶基等,含有破折線部之鍵結代表雙鍵或單鍵。無
