Appearance / Identification
Different harvester ant species exhibit different colors, ranging from reddish-brown or yellow to black.
Characteristics: Each species of harvester ants has a head, antennae, thorax, abdomen and a segmented pedicel located between the thorax and abdomen.
Other species-specific characteristics include the enlarged heads of workers and the presence of a psammophore, which are rows of long hair on the ventral side of the head that harvester ants use for storing soil and seeds. Not all species of harvester ants have this beard-like feature.
Why Are They Called Harvester Ants?
All species of harvester ants practice the unique nesting habit of clearing the vegetation around the nest site before constructing the above-ground mound. Some species clear an area as large as 23 feet in diameter.
Do They Bite or Sting?
Though not aggressive by nature, the harvester ant can deliver an especially painful sting.
Class: Insecta; Order: Hymenoptera; Family: Formicidae
What Areas of the Country Do They Live?
In the United States, harvester ants tend to populate arid grasslands and deserts in the western part of the country. The Florida harvester ant is the only species to occur east of the Mississippi River. California and Texas are home to especially large populations of this pest.
What Do They Eat?
Harvester ants feed on a range of seeds. Some of the most common food sources include ragweed, crab grass, rough buttonweed, sedge, poke weed, red clover, alfalfa, evening primrose, narrow leaf vetch and crotonweed.
Like many insects, harvester ants reach full maturity by way of complete metamorphosis. The four developmental stages of egg, larva, pupa and adult last different amounts of time for different species.
Workers, winged reproductives and a single queen comprise the typical harvester ant colony.
Reproductive adults swarm, mate and form new colonies any time between June and October.
How Long Do They Live?
The pests are unusually long-lived. Harvester ant colonies have been recorded to last at least 19 years, while the queens of some species live as long as 17 years.
Dangers / Problems
Although harvester ants rarely infest homes, the pests frequently construct mounds and nests on golf courses, in lawns, in open fields, or on playgrounds.
When mounds are disturbed, the worker ants attack by stinging repeatedly. The sting of the harvester ant induces an extremely painful and long-lasting reaction and has even been fatal to children.
Signs of Infestation
Harvester ants are not subtle creatures. Since they feed on grass seed, colonies strip large sections of vegetation from the land around their nests. In naturally grassy areas, a disturbance is easy to spot as a clear sign of a harvester ant infestation. Additionally, the pests cover the nest entrance with an elaborate mound, which makes an infestation even easier to detect.
How Do You Find Them?
- May notice a lack of vegetation in an infested area.
- Look for the presence of mounds covering nests.
- May experience repeated and painful stings inflicted by the pests.
Preventing harvester ants from becoming a major problem largely consists of avoiding the pests altogether. Unless they pose a stinging threat to children or pets, the otherwise harmless insects should simply be avoided. Since harvester ants do not behave aggressively unless provoked and because their nests are usually easy to spot, individuals should have no problem preventing disturbances.
How Do You Get Rid of Them?
Though harvester ants do not invade homes, the pests may infiltrate yards and other outdoor areas. The use of baits helps control infestations. Harvester ants use odor trails and the orientation of the sun to locate food sources, and placing baits along the paths they travel can help keep the size of the colony in check. Individuals suffering from a harvester ant infestation may also consider contacting a pest control professional to treat the mounds with insecticide.
Harvester ants make their nests in the ground in open, sunny areas. Some species make only one opening to the nest. The workers clear away the vegetation around the nest. The clear space can be more than 30 feet in diameter.
Some species of harvester ants place stones, sticks, and pieces of dead grass on the soil in the area that they have cleared. Scientists suspect that the debris absorbs heat and helps to heat the nest that is underground. During the year, as the angle of the sun changes, the workers may move the nest if the area becomes shady.
The workers excavate galleries and tunnels under the ground. Scientists found one nest that extended more than ten feet into the soil. The workers take the soil out of the nest as they dig the tunnels. Some species build a mound with the excavated soil. Other species carry the soil away from the nest opening.
Harvester ant workers collect seeds. In the dry environment of the southwestern United States, harvester ants are probably the major seed predator. The ants are able to compete successfully with mammals, like mice, for seeds.
This seed gathering is the reason these ants were given their common name of “harvester”. The workers bring most of the seeds back to the nest. However when they find the seeds of some plants, they remove part of the seed for food and discard the rest. Harvester ants can cause crop damage by taking the seeds of wheat and oats. They also take seeds from alfalfa, Johnson grass, mesquite, and Bermuda grass.
If a harvester ant worker finds some seeds, she first tries to pick one up. If the worker can pick up one of the seeds, she starts back toward the nest. Along the way, she leaves a trail of a chemical called a pheromone. The scent of the pheromone will mark the way back to the seeds. When she reaches the nest, she recruits other workers to return to get the rest of the seeds.
If a harvester ant worker finds seeds that are too large for her to carry alone, she “calls for help” by releasing a pheromone into the air. Other harvester ant workers respond to the smell of the pheromone and come to help.
Red harvester ants are very large ants. When winged specimens come flying around, people pay attention. Scientists call the winged ants alates. Since they come out of their nest in large numbers, many people call them swarmers.
The winged ants only have one purpose. They leave their nest to find a mate from another colony. After they are inseminated, the females will start new colonies. These inseminated female ants will be the queens in the new colonies.