The Edwin S. George Reserve is located in southern Michigan. Here live a very large number of species of ants for an area this far north and consisting of only two square miles. This large number of species is apparently owing to the variety of terrain which has resulted from glacial activity.
"A List of the Ants (Hymenoptera: Formicidae) of the Edwin E. George Reserve, Livingston County, Michigan,"
The Great Lakes Entomologist, vol 8
Available at: https://scholar.valpo.edu/tgle/vol8/iss4/11