Local Distribution of Formica Ulkei Moundnests With Reference to Certain Ecological Factors

The existence of a number of mound-nest colonies of the ant Formica ulkei Emery at Palos Park, Illinois, has been known for several decades. In recent years various phases of ecology and physiology of this ant and its nests have been analyzed and published. Holmquist (1928) reported at length on its life-history and hibernation; Orlando Park (1929) discussed certain myrmecocoles associated with it in the nests; Thomas Park (1929) reported the occurrence and behavior of a thief-ant intimately found in the mounds, and Dreyer (1932) has analyzed certain aspects of the respiratory behavior of this ant in relation to its hibernation. Up to the present time no accurate description of the extent and distribution of these mounds has been attempted. In this paper they will be discussed with reference to their individual form, their distribution, and certain environmental factors correlated with this distribution.