There has been a demand for the development of novel agricultural and horticultural insecticides because pests and the like still cause heavy damage to crops produced in agriculture, horticulture, and the like, and pests resistant to existing chemical agents have emerged, etc. Under these circumstances, the present invention provides: an agricultural and horticultural insecticide containing, as an active ingredient, a 3H-pyrrolopyridine compound represented by general formula (1) (in the formula, A1, A2, and A3 each represent a nitrogen atom or a CH group, R1 represents an ethyl group, R2 and R4 each represent a hydrogen atom, R3 and R7 each represent a haloalkyl group, R5 and R6 each represent a fluorine atom, and m represents 0 or 2.) and an N-oxide thereof, or salts thereof； and a method for using the agricultural and horticultural insecticide.
