Army ants, Neivamyrmex nigrescens, from Mokelumne Hill
These ants were found in the cemented basement area of a house between Mokelumne Hill and San Andreas. There was a trail on two sides of an interior wall. Collected by Travis Magruder. 4 May 2023.
Dr Philip Ward identified them, via photos, as army ants, Neivamyrmex nigrescens.
This links to another page on our site, showing army ants in the Sierra Nevada foothills. But those ants are of a differnet army ant species, Neivamyrmex opacithorax. according to Dr. Ward, the basal margin of the mandible rounds gradually into the masticatory margin of the mandible in N. nigrescens, but not N. opacithorax.