A FIELD-STUDY OF THE NESTING ECOLOGY OF THE THATCHING ANT, FORMICA OBSCURIPES FOREL, AT HIGH-ALTITUDE IN COLORADO

A field study of the thatching ant, Formica obscuripes Forel, at 2560 m elevation in Colorado provided information on mound density composit ion, dimensions, and temperatures; worker longevity; and mite parasiti zation. Density was 115 mounds/ha. Mounds had 1-52 entrances and Perom yscus fecal pellets in the thatch. Mounds conserved heat and exhibited thermal stratification. Excavations of 4 nests revealed depths of 0.3 m to almost 1 m, novel myrmecophiles, and 0-198 wingless queens per n est. Marking experiments demonstrated that some workers overwinter and live more than a year.