an object of the present invention is to provide and develop novel agricultural and horticultural insecticides in view of the still immense damage caused by insect pests etc . and the emergence of insect pests resistant to existing insecticides in crop production in the fields of agriculture , horticulture and the like . provided are a condensed heterocyclic compound represented by the general formula : or a salt thereof ; an agricultural and horticultural insecticide comprising the compound or a salt thereof as an active ingredient ; and a method for using the insecticide .