Red Harvester Ants

Text and Photos by Laurie Sheppard

Ants! They get into your pantry. They invite themselves to your picnics. Some of them can chew through a wood framed house. Others sting!! What’s to like about an ant?? Well, maybe if it was a mostly peaceful ant that didn’t enter homes, chew on wood, or sting when you get near their nest, you could like it. The Red Harvester Ant is that sort of ant.

Although Red Harvester Ants look formidable because of their size and wasp-like appearance, they are communal seed-eaters that mostly keep to their own business. If you have walked the Haller Haven Trail, at Hagerman National Wildlife Refuge,  out to Dead Woman Pond, you have passed a broad, flat nest of Red Harvester Ants that stretches a few feet across. They are the large, busy, red ants that never stop moving as you pass. They are capable of delivering a painful bite if threatened, but they are not aggressive and are generally reluctant to do so.

Red Harvester Ants are a favorite food source for the Texas Horned Lizard and they are in constant competition for food and territory with other ants such as the invasive Fire Ant. Sometimes Red Harvester Ant nests are created in risky areas and do not survive. Often, that is because of human actions, either intentional or accidental. Red Harvester Ant colonies have been declining in recent years and that decline has impacted other native species.

Each underground Red Harvester Ant nest is composed of many chambers connected by labyrinthine tunnels that have been excavated by members of the colony. A mature nest can reach depths of over 8 feet and is several feet across. Within the nest, the colony consists of a single queen, who can live for 15-20 years, and thousands of female worker ants. Only the queen can reproduce and she is well cared for by the others, for her death signals the end of the colony.

For the first four to five years, a new queen produces only sterile female worker ants. These ants perform the tasks that ensure the success of the nest: foraging for seeds, maintenance and excavation of the physical infrastructure, caring for the queen and her larvae, and defense of the nest. When the colony reaches about 10,000 members, the queen produces a small number of males and fertile females. She will do this once per year for the remainder of her life.

These unique ants, called alates, have wings that will carry them away from the nest to an aggregation site. The site is created when a few males mark a location with specialized pheromones that trigger sexual behavior. These pheromones attract other males, who add more pheromones, and also draw females to the site. There, alates from many nests engage in a mating ritual that will result in new colonies being formed. Each female mates with multiple males of separate lineages, then flies to a suitable spot to establish her own nest. She digs down several inches and produces her first larvae, which become the nest’s original worker ants. The workers excavate the nest and gather food for their colony before moving deep underground for the winter.

In spring, the work continues. Scouts leave the nest each morning to look for food sources, leaving a trail of pheromones for the foragers to follow. The ants in the nest appear to have a sense of time. If a scout comes back too quickly, the forager ants sense danger and ignore that route. If a scout takes too long to return with seeds, then perhaps foraging will expend more energy than the value of the seeds they may collect. The foragers are therefore selective in the trails they follow. The work of these ants benefits the ecosystem by scattering some of the seeds they gather as they return to the nest. Meanwhile, excavation and nest cleaning are constant.

It’s easy to think that the frenetic pace of the ants lacks purpose, but as you watch individual ants marching out of the nest carrying staggering loads or returning to the nest dragging stalks heavy with seeds, you realize what an amazing society this is. Ants can carry up to 20 times their body weight. For every ant you see, there are several others that are working in the total darkness below the surface. Each ant will defend the nest to her death when called upon. Next time you see a Red Harvester Ant nest, stop and spend a few minutes getting to know them.

NOTE: Laurie Sheppard is a regular volunteer at Hagerman NWR and frequent contributor to the FOH Blog. She is a Texas Master Naturalist, member of the Blackland Prairie Chapter.