(Uploaded by Plazi for the Bat Literature Project) Before 2004, there were no records of evening bats (Nycticeius humeralis) from northern Indiana and northern Ohio and, although three records existed for Michigan, these bats were believed to be vagrants or lost migrants. In August 2004, however, we discovered a maternity colony consisting of at least 68 evening bats in Lenawee County, Michigan. The colony is located over 300 km from the nearest extant colony in Hendricks County, Indiana, and it is the northernmost on the continent. The lack of a large continuous riparian corridor, lined with suitable bottomland forest and connecting the Ohio River with the southern Great Lakes area, probably contributes to the rarity of evening bats across northern Indiana, northern Ohio and southern Michigan.