Mesoionic pyrido [1, 2-A] pyrimidine pesticides

Disclosed are compounds of Formula 1, wherein R 1 is phenyl or pyridinyl, each optionally substituted with Q and up to 3 substituents independently selected from R 2 ; each R 2 is independently halogen, cyano, SF 5 , C 1 -C 4 alkyl, C 1 -C 4 haloalkyl, C 1 -C 4 alkoxy, C 1 -C 4 haloalkoxy, C 1 -C 4 alkylthio or C 1 -C 4 haloalkylthio; and Q is phenyl or pyridinyl, each optionally substituted with up to 5 substituents independently selected from the group consisting of halogen, cyano, C 1 -C 4 alkyl, C 1 -C 4 haloalkyl, C 1 -C 4 alkoxy and C 1 -C 4 haloalkoxy. Also disclosed are compositions containing the compounds of Formula 1 and methods for controlling an invertebrate pest comprising contacting the invertebrate pest or its environment with a biologically effective amount of a compound or a composition of the invention. Further disclosed are methods for increasing vigor of a crop plant comprising contacting the crop plant, the seed from which the crop plant is grown or the locus of the crop plant with a biologically effective amount of a compound or composition of the invention.