Biology, Ecology, and Host Specificity of EuropeanAphthonaspp. (Coleoptera, Chrysomelidae) Used as Biocontrol Agents for Leafy Spurge,Euphorbia esula(Euphorbiaceae), in North America

Leafy spurge (Euphorbia esula) is an herbaceous perennial of European origin that was accidentally introduced into North America where it has become a serious weed in pastures and rangelands. Five species of root-feeding chrysomelid beetles in the genusAphthonahave been released in North America for the biological control of leafy spurge. They originate from central and eastern Europe and occur in different habitats. The brown species,Aphthona cyparissiae, Aphthona flava,andAphthona nigriscutis,occur predominantly in open dry habitats, and the black species,Aphthona czwalinaiandAphthona lacertosa,prefer moister habitats. All five species are univoltine and overwinter as larvae. The host range of these fiveAphthonaspecies is restricted to species in the subgenusEsula.