Facts, Identification & Control
Prevalent throughout North America, harvester ants belong to the genus Pognomyrmex and are generally known for their seed-collecting behaviour and the painful sting they impart. The scientific genus name of these insects means “bearded ant,” which alludes to the fringe of hairs called psammaphore that lines the underside of the surface of the head. Harvester ants use the hairs to carry soil and seeds, though not all species of pogonomyrmex ants possess the feature.
Appearance / Identification
Members of the worker caste in harvester ant colonies are large, ranging from 4.5 to 13 mm in length. Some workers have large, squarish heads, while others appear more rounded. Harvester ants vary in colour depending on the species and can be red, black, or brown. The insects each possess a two-segmented pedicel and a stinger. Queens and mating males are larger than workers and have two sets of wings prior to breeding.
Found throughout the United States, certain species of harvester ants also live in Canada, including the red harvester ant. The insects build nests in the soil and prefer to live in open areas, such as plains. Their nests typically have a single opening surrounded by an area stripped of vegetation that measures up to 2 m in diameter.
Harvester ants mainly feed on gathered seeds. They also eat other small insects and arthropods, dead or alive.
Life Cycle / Reproduction
Like other ant species, harvester ants mate by swarming. Queens and males known as alates, or winged ants, typically swarm in late summer. Males die after mating, while the females detach their wings, dig new nests, and deposit the eggs that will hatch into larvae before eventually developing into workers. The workers then take over maintaining the nest and feeding the new larvae that the queen produces. Some nests may eventually grow to include thousands of harvester ants.
Problems Caused by Harvester Ants
Although they do not typically invade homes, harvester ants are pests on lawns and even playgrounds. The insects can damage crops, affect rangelands, and even hurt cattle. In areas where nesting occurs, the vegetation may be severely stripped, which contributes to soil erosion. Harvester ant nests located near roadways and airport runways have also been known to cause potholes. Additionally, their painful sting may lead to anaphylactic reactions in both humans with known allergies and animals that come into contact with nests.
Detection / Signs of Infestation
The most common sign of a harvester ant infestation is often the areas of stripped vegetation that surround the nests and mounds. Certain species have been known to build mounds as large as a metre high and five metres across. As the insects are not known to enter homes except to occasionally forage for new food sources, human contact sometimes only occurs when people are stung by the pests.
Since harvester ants do not infest homes, the implementation of preventative measures may not even be necessary. Selective treatment of exterior sites with appropriate insecticide may help keep the insects from building nests in the yard. Other steps may be taken just in case, such as sealing cracks and crevices, repairing window and door screens, and keeping vegetation and mulch away from the foundation of the home.
Control / Removal
Controlling harvester ant infestations without professional assistance may prove difficult due to the potentially large size of the colony and the stinging capabilities of the insects. Experienced pest control professionals, however, have the training, know-how, and access to the most effective treatment options to eliminate harvester ants safely and properly.