Species composition of Erythroneura leafhoppers infesting the 3 major classes of grapes grown in New York was investigated. Eastern grape leafhopper, E. comes (Say), comprised 74-100% of populations collected on the native American (VitL~labmsca Bailey) cultivars 'Concord', 'Niagara', 'Catawba' and 'Delaware'. On interspecific hybrid (Vitis sp.) and Vitis vinifera L. cultivars, E. comes was largely absent, and 97-100% of lea/1lOppers collected were 2 cryptic species, E. bistrata McAtee and E. vitifex Fitch. On the native American variety 'Elvira', a V labrusca X V riparia Michaux hybrid, field populations were 24% E. comes and 74% the E. bistrata/vitifex complex. E. vitis (Harris), E. tricinta Fitch, and E. vulnerata Fitch were also present in commercial grapes, but never exceeded 20% of the populations sampled. Populations on wild V npana adjacent to vineyards were comprised of 24% E. comes, 47%E. histrata/vitifex, 19% E. vitis, and 10% E. tricinta. Dissection revealed that proportions of E. bi';trata and E. vitifex in field collections, varied from 97% E. bistrata to 61% E. vitifex.Oviposition of E. comes and E. bistrata on V vinifera, interspecific hybrid, and native American cultivars was compared in greenhouse choice tests and field no-choice tests. In choice tests, E. comes laid more eggs on Concord and Elvira than on the interspecific hybrid 'Seyva! blanc', or the V vinifem cultivar 'White Riesling'. E. bistrata did not oviposit on Concord when paired with either Elvira, Seyval blanc or White Riesling. When caged to grape leaves in no-choice tests, E. curlles laid the most eggs on native American cultivars and the fewest on V vinifem and interspecific hybrids; E. bi';trata laid the most eggs on hybrid~md V vinifem cultivars, and very few eggs on three native American cultivars. These results show that E. bistrata and E. vitifex are the principal pest species on V vinifera and many interspecific hybrid cultivars in New York, and that E. cumes is the principal leafhopper pest on native American V labrusca cultivars.