The known ants of the state of Idaho comprise about 73 named species, subspecies and varieties. They occupy a wide variety of habitats ranging from dunes of pure sand, barren and wind-blown, to forests of yellow pine, fir and spruce, with an abundance of shade and moistuce. Because of the large amount of vegetation in the montane forests and subalpine pine meadows a large percentage of the ant fauna lives there, if not exclusively at least in very great numbers. It is, however, rather surprising to observe the large number of species which nest on the dry plains of sagebrush, bromegras and rabbitbrush, and on the scattered alkaline flats of greasewood in the southern part of the state.