Evening bats (Nycticeius humeralis) are ubiquitous in the southeastern United States, but only one maternity colony occurs in the Great Lakes region, in Michigan, and it is the northernmost colony known in North America. We hypothesized that diet would vary throughout the season and between years and that diet of evening bats in northern areas would differ from diet of those in more southern parts of the continent. Almost 600 fecal pellets of evening bats were collected and analyzed from May through August 2006–2007. Thirteen orders of insects and two orders of arachnids were found, but Coleoptera, Diptera, Hymenoptera, and Hemiptera composed 87% of dietary volume. Lepidoptera, which forms a substantial portion of the diet for most vespertilionids in eastern North America, contributed only 4.7% to the volume. Diet was broadly similar to evening bats in the core of their range, although evening bats in Michigan incorporated substantially more Diptera into their diet. Dietary composition and diversity differed little between years but showed variation among weeks within years. The lack of dietary specialization and similarity in major components in different parts of the range suggest that availability of prey or dietary competition with other species at the ordinal level are not factors limiting the northern distribution of the evening bat.