NOVELTY - A pyridine compound (I), is new.    USE - New pyridine compound useful in agent for controlling pest, insects, acarids, and ectoparasite (all claimed) including Plutella xylostella, planthopper, leafhopper and Nilaparvata lugens.    ADVANTAGE - The pyridine compound is environmentally-friendly, delays development of drug resistance with respect to insects, and does not cause damage to plant, livestock e.g. cow, fish, and human.    DETAILED DESCRIPTION - A pyridine compound or its salt of formula (I), is new.    R1=1-6C haloalkyl or 1-6C alkoxy;    X1=1-6C alkyl, 2-6C alkenyl, 2-6C alkynyl, 3-8C cycloalkyl, hydroxy, 1-6C alkoxy, 1-7C acyl, 1-6C alkoxycarbonyl, amino, 1-6C alkylthio, 1-6C alkyl sulfinyl, 1-6C alkylsulfonyl, 6-10C aryl, 3-6 membered heterocyclyl, halo, cyano or nitro (all optionally substituted);    m=0-3;    R2=1-6V alkyl, 2-6C alkenyl, 2-6C alkynyl, 3-8C cycloalkyl, 4-8C cycloalkenyl, hydroxy, 1-10C alkoxy, 2-6C alkenyloxy, 2-6C alkynyloxy, 1-7C acyl, carboxy, 1-6C alkoxycarbonyl, amino, aminocarbonyl, 1-6C alkylthio, 6-10C arylthio, 1-6C alkyl sulfinyl, 6-10C aryl sulfinyl, 1-6C alkylsulfonyl, 1-7C acyloxy, 1-6C alkoxycarbonyloxy, aminocarbonylloxy having substituent, amino(thiocarbonyl)oxy having substituent, 1-6C alkyl sulfonyloxy, 6-10C aryl, 6-10C aryloxy, 3-6 membered heterocyclic group, imino 1-6C alkyl, 1-6C alkylidene aminoxy, N-cyano-S-(1-6C alkyl)sulfine imidoyl, N-cyano-S-(1-6C alkyl)sulfone imidoyl, halo, cyano or nitro;    X2=1-6C alkyl, 2-6C alkenyl, 2-6C alkynyl, 3-8C cycloalkyl, oxo, hydroxy, 1-6C alkoxy, 1-7C acyl, 1-6C alkoxycarbonyl, amino, 1-6C alkylthio, 1-6C alkyl sulfinyl, 1-6C alkylsulfonyl, 6-10C aryl, 3-6 membered heterocyclyl, halo, cyano or nitro;    n=0-3;    Z=O, sulfur atom, sulfinyl, sulfonyl, or NR3;    R3=H, 1-6C alkyl, 2-6C alkenyl, 2-6C alkynyl, 3-8C cycloalkyl, 1-7C acyl, 1-6C alkoxycarbonyl, 1-6C alkylsulfonyl, 6-10C aryl, 3-6 membered heterocyclyl, or cyano;    A=1-6C alkylene;and    R2+A=ring having carbon atom.