Stiriinae as presently circumscribed include two tribes, the Annaphilini and nominate Stiriini, that have radiated over the American West and Mexico, where more than 90% of the global species diversity is believed to be endemic. Here we provide life history information for 56 species of Stiriini that occur north of Mexico—40 are figured for the first time. For each species, we provide a brief summary of the known distribution north of Mexico, its seasonal phenology, known larval hosts, and diagnostic features. Images of a penultimate or last instar are provided for all but one species. Additionally, we include a brief characterization of Stiriini larval morphology, summarize common elements of Stiriini larval biologies, and identify 16 species that might be worthy conservation targets.