A key and diagnoses are provided for the North American species of Scelolyperus Crotch. Descriptions are given for Scelolyperus pasadenae, new species from California and Scelolyperus tetonensis, new species from Wyoming. Luperus morriaoni Jacoby is treated as a junior synonym of Luperus varipes LeConte, Luperodes nigrovirescens Fall is treated as a junior synonym of Luperus nigrocyaneus LeConte, and Scelolyperus chautauquus Wilcox is treated as a junior synonym of Scelolyperus liriophilus Wilcox, new synonymies. Luperus lecontii Crotch is transferred to Scelolyperus, new combination. Distributional and biological data are provided for each species
