1. A composition for controlling agricultural pests, containing as an active ingredient a derivative of α-alkoxyphenylacetic acid represented by the formula (1):! ! where X1 represents a methyl group, a difluoromethyl group or an ethyl group； X2 represents a methoxy group or methylamino group； X3 represents a phenyl group, a 2-methylphenyl group or a 2,5-dimethylphenyl group! and a neonicotinoid compound represented by the formula (2):! ! where A represents a 6-chloro-3-pyridyl group, a 2-chloro-5-thiazolyl group, a tetrahydrofuran-2-yl group or a tetrahydrofuran-3-yl group； Z represents a methyl group, an NHR2 group, an N (CH3) R2 group or an SR2 group； R1 represents a hydrogen atom, a methyl group or an ethyl group； R2 represents a hydrogen atom or a methyl group； or R1 and R2 together may form a CH2CH2 group or a CH2OCH2 group； X represents a nitrogen atom or a CH group, and Y represents a cyano group or a nitro group. ! 2. The agricultural pest control composition according to claim 1, wherein the neonicotinoid compound represented by the formula (2) is selected from the group consisting of clothianidin, imidacloprid and thiamethoxam. ! 3. The agricultural pest control composition according to claim 1 or 2, in which the mass ratio of the α-alkoxyphenylacetic acid derivative represented by the formula (1) to the neonicotinoid compound represented by the formula (2) takes values in the range from 0.0125: 1 to 500: 1. ! 4. A method of controlling agricultural pests, comprising using an effective amount of an α-alko derivative1. Композиция для борьбы с сельскохозяйственными вредителями, содержащая в качестве активных ингредиентов производное α-алкоксифенилуксусной кислоты, представленное формулой (1): ! ! где Х1 представляет собой метильную группу, дифторметильную группу или этильную группу； Х2 представляет собой метоксигруппу или метиламиногруппу； Х3 представляет собой фенильную группу, 2-метилфенильную группу или 2,5-диметилфенильную группу ! и неоникотиноид
