These are native ants in the western U.S.
As with most other harvester ants the California species rarely enters structures. They restrict their diet to seeds found outside, and forage at dusk for these natural foods. In agricultural fields they may be a problem as they gather seeds intended as crops. The nest usually is seen as one or more holes surrounded by a wide, cleared circle with a ring of soil at the perimeter. The harvester ants are capable of stinging but would do so only when directly threatened, such as when confined within clothing or if a person stands or sits on a nest opening or on foraging ants. They most often are found in dry climates and create nests deep underground. The soil above may be covered with debris to help maintain the proper climate in the nest. There is a single queen and the workers are monomorphic.
These are relatively large ants, about ¼ inch long and solid mahogany red. They have large mandibles for carrying and crushing seeds and have a “beard” of long hairs around the base of the head on each side. A medium length, sharp pair of spines will be present at the back of the thorax on top.
Characteristicts Important to Control:
When these ants are a threat to people or pets active in their nest areas the nest can be treated directly using dust or spray or drench, as well as a contact granular insecticide around the area of the nest. Harvester ants also will accept granular insect baits that can be applied as labeled around the nest openings.