A total of 605 species of leafhoppers, including 38 exotics, are documented for New Hampshire. Nine additional species are included that were taken 1–16 km from the NH border in Maine, Massachusetts, and Vermont. There are 287 new records for the state of which Empoasca vitis (Göthe) is new for the Nearctic region, and two others are new for the USA: Idiocerus albolinea Hamilton, here recorded also from Montana, and Gyponana quebecensis Provancher, also newly recorded from Illinois, Maine, Montana, Utah, and Vermont. Six new state records are documented for Massachusetts, and eight additional new state records for Maine. Eight species are here described in Typhlocybinae by Chandler: Dikrella scimitar, Empoasca kittelbergeri, Empoasca murrayi, Eratoneura hampshirensis, Erythridula bassorum, Erythridula morsei, Erythroneura confusa, Erythroneura viridis; and six by Hamilton in the other subfamilies: Chlorotettix smodix, Jikradia brikelos, Gyponana castor, Gyponana pollex, Macrosteles hizemus, and Macrosteles wahnapitae (new species). Oncopsis ferrosa Hamilton, 1983 is raised from subspecies to species (new status). Erythroneura alternata Johnson, 1935a (now in genus Erythridula) is recognized as the senior synonym of Erythroneura cauta Johnson, 1935b, synonymy reversed based on precedence of publication date (revised synonymy); five junior synomyns of Xestocephalus desertorum (Berg) are raised from synonomy: X. brunneus Van Duzee, X. fulvocapitatus Van Duzee, X. nigrifrons Osborn, X. similis Peters, and X . superbus (Provancher) (revised status); a junior synonym of Penthimia americana Fitch, 1851, P. vicaria Walker, 1851 is removed from synonymy and placed as a subspecies of P. americana (new status); Empoasca pergandei Gillette, 1898 is placed in Kyboasca Zakhvatkin (new combination).
Specimen data are given, as well as summaries of the collection data and seasonality of the adults. Species richness is highest in habitats based on sandy soils such as eskers and glacial outwash plains. A list of leafhopper (Cicadellidae) species erroneously attributed to New Hampshire is provided, as is a list of the leafhopper species occurring in the surrounding states and the adjacent Atlantic Maritime Ecozone of Quebec that have not yet been taken in New Hampshire. A comparison of the collecting techniques used for sampling species in New Hampshire agroecosystems support the use of multiple collecting techniques for biodiversity studies, such as sweeping, pan traps, and sticky traps, as each produced species not taken by the other techniques. Yellow traps were the most attractive to the largest number of species, with green comparable for some of these species. Red and blue pan traps were often the most attractive to species that feed at ground level and do not readily fly. The plant hosts of the New Hampshire species are also provided with a list of the species that feed on them. COI barcodes are used to investigate species complexes of Draeculacephala, Jikradia, and Penthimia.