The present invention addresses the problem of developing and providing a novel agricultural or horticultural insecticide, because in crop production in agriculture, horticulture, etc., damage caused by pests, etc. is still serious and because of, for example, the growth of pests having resistance to existing pesticides. Provided are: a fused heterocyclic compound represented by general formula (1) or a salt thereof； an agricultural or horticultural insecticide containing the compound or salt as an active ingredient； and a method for using the insecticide. (In the formula, R1 represents an ethyl group； R2 represents a cycloalkyl group； R3 represents a haloalkyl group； A, A2, and A3 each represent a nitrogen atom or a CH group； A1 represents N-Me； m is 0 or 2； and n is 1.).在農業及園藝等之作物生產中，因害蟲等所致的損害現今仍大，因此本發明係由於對既有藥劑有抵抗性之害蟲的產生等主要因素，而以開發、提供新穎的農園藝用殺蟲劑為課題。提供通式(1)所表示之稠合雜環化合物或其鹽類、將其作為有效成分之農園藝用殺蟲劑以及其使用方法。{式中，R1表示乙基，R2表示環烷基，R3表示鹵烷基，A、A2、及A3表示氮原子或CH基，A1表示N-Me。m表示0或2，n表示1}。
