MJ Hatfield and I yesterday visited a large complex of Formica exsectoides mounds originally reported from this site in 1969, forty years ago (Christensen and Quick 1970, Quick and Christensen 1972; citations below). It was a wooded horse pasture then but is now a state wildlife area. We found numerous mounds spread over several acres, casually counting approximately 90 mounds, but we estimate that many more exist beyond the sightline of the route we walked. They ranged greatly in size from ~6 inches high and 1 foot in diameter to 2.5 feet high and 8 feet in diameter. The ants were busy repairing their mounds, which had been saturated by several inches of rain over the past few days.

Christensen, C.L. and K.M. Quick. 1970. Report on Formica exsectoides in Hamilton County. Proceedings of the Iowa Academy of Science 77:207-209.

Quick, K.M. and C.L. Christensen. 1972. A further note on Formica exsectoides. Proceedings of the Iowa Academy of Science 78:43.