THE USE OF ANT NESTS BY SUBTERRANEAN TERMITES IN 2 SEMIARID ECOSYSTEMS

A subterranean termite, Reticulitermes tibialis, was found in nests of the western harvester ant (Pogonomyrmex occidentalis) in two semiarid ecosystems. We partially excavated 23 ant nests in the shrub-steppe o f southwestern Wyoming during 1987 and 31 nests in the shortgrass-step pe of northeastern Colorado during 1991. No termites were collected fr om ant nests during July at either site, but termites occurred in 62% of nests in Wyoming and 65% of nests in Colorado during September. We chose an additional 28 ant nests at the Wyoming site to assess whether use of toilet-paper baits by termites was affected by proximity to an t nests. Our findings suggest that termites frequently use ant nests a s ant activity decreases in the autumn, but do not strongly prefer ant mounds to nonmound sites.