A water-based pesticidal suspension comprises (a) flonicamid, (b) a polycarboxylate surfactant, (c) a sulfonate surfactant, and (d) water. The sulfonate surfactant (c) is at least one member selected from the group consisting of an alkyl sulfosuccinate, a lignosulfonate, a C8-18 alkyl benzene sulfonate and a C8-18 alkyl diphenyl ether disulfonate. An average particle size of the volume distribution of (a) flonicamid is preferably from 0.5 μm to 10 μm. The polycarboxylate surfactant (b) is preferably a sodium salt of maleic acid/olefin copolymer.
