Abstract
Hundreds of ant-nest bare-mineral-soil mounds, as well as ant plant litter 'thatch' mounds, are distributed across the sagebrush-steppe rangeland on Goodale's Cutoff along the Oregon Trail near Arco, Idaho, adjacent to the northern boundary of Craters of the Moon National Monument and Preserve. US Natural Resources Conservation Service personnel and local landowners wanted to determine if these ants were exotic invasive pests that could damage rangeland pasture and grazing habitat or impact historic anthropogenic artifacts. Four species of native ants, Pogonomyrmex salinus, Formica limata, F. obscuripes, and F. ravida, which are common on the Snake River Plain of Idaho, were collected from different mounds. Another native ant, Solenopsis molesta, was foraging around the perimeter of one thatch mound. Additionally, a subterranean termite, Reticulitermes tibialis, common in the western United States and widespread within Idaho rangelands and mountains, was found foraging within both types of ant mounds. This study provides insight into ant and subterranean termite activity on the Snake River Plain.