Significantly more leafhoppers, especiallyAmbylsellus curtisii(Fitch),Doratura stylata(Boheman),Draeculacephala antica(Walker),Graminella nigrifrons(Forbes),Endria inimica(Say), andMacrosteles fascifrons(Stål), were collected from nitrogen fertilized (480 kg N/ha) than from unfertilized plots of 3 grass cultivars out of 39 in 1971 and 9 out of 23 N-fertilized (240kg N/ha) cultivars in 1972. Also, more grasshoppers,Dicromorpha viridisScudder,Melanoplus bivittatus(Say), and anotherMelanoplusspecies; the flea beetles,Chaetocnema pulicariaMelsheimer andSystena frontalis(F.); and the frit fly,Oscinella frit(L.), were collected in significantly higher numbers on some N-fertilized cultivars.Peak numbers of most insect species occurred in late summer. Carbofuran (10% granules, 2.24 kg AI/ha in 1972) and (flowable, 1.12 kg AI/ha in 1973) reduced mean numbers of most species of insects and resulted in increased dry matter yield of a few cultivars both years.