Provided is a composition having an excellent pest control effect. This composition contains a condensed heterocyclic compound represented by the following formula (1) and an isoparaffin being a liquid at 25℃, atmospheric pressure condition: wherein, R1 represents hydrogen atom, a C1-3 alkyl group optionally having one or more than one halogen atom, a halogen atom, a C1-C3 alkoxyl group, a C2-C4 alkoxylcarbonyl group, S(O)mR2, NR3R4, a nitro group or a cyano group, R2 represents a C1-C3 alkyl group, R3 and R4 are the same or different, each represents hydrogen atom or a C1-3alkyl group. n represents 0, 1 or 2, m represents 0, 1 or 2.本發明提供對有害生物顯示優異防治效果的組成物。一種有害生物防治組成物，其係含有式(1)表示的縮合雜環化合物，及在25℃大氣壓條件下為液態的異烷烴：式中，R1表示氫原子、可具有1個以上鹵原子的C1-C3烷基、鹵原子、C1-C3烷氧基、C2-C4烷氧羰基、S(O)mR2、NR3R4、硝基或氰基，R2表示C1-C3烷基，R3及R4是相同或互不相同，表示氫原子或C1-C3烷基，n表示0、1或2，m表示0、1或2。
