Great Basin Naturalist


A field study of the thatching ant, Formica obscuripes Forel, at 2560 m elevation in Colorado provided information on mound density, composition, dimensions, and temperatures; worker longevity; and mite parasitization. Density was 115 mounds/ha. Mounds had 1–52 entrances and Peromyscus 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 nest. Marking experiments demonstrated that some workers overwinter and live more than a year.