Size: This type of ant has two distinct sizes of workers. The larger ones, called major workers, typically range in size from 1/8-inch to ¼-inch in length, depending on the species. The major worker is easily identified by the extremely large size of the head in comparison to its body. The head of the minor worker is in proportion to its body.
Color: Most are reddish brown in color. The minor workers can resemble fire ants except that big-headed ants have 12 segments in their antennae while fire ants have only 10 segments.
Behavior: Big-headed ants, like all ants, establish well-defined trails between the nest and food and water sources. They feed on a wide variety of foods including dead insects, plant materials, and garbage. The workers are partial to the sweet honeydew produced by aphids, scales, and mealybugs found feeding on many trees and plants. Fruit trees, roses, and many shrubs serve as hosts for aphids and may contribute to ant infestations in homes and other buildings.
Habitat: Big-headed ants are soil-nesting ants, most commonly found nesting outdoors beneath stones, logs, and landscape timbers. These ants are also commonly found inside the soil of potted plants, and many infestations may be traced to planters. In addition, big-headed ants may be found nesting beneath slab foundations and entering through cracks in the slab. On occasion, these ants will nest inside rotted wood or will excavate old termite-damaged wood to make a nest.
Tips for Control: Because big-headed ants are soil nesters, their colonies are often easy to see due to the piles of displaced soil formed as they excavate tunnels in the ground. Most colonies are relatively small and easy to treat, but treating infestations involving multiple colonies require experience. General tips for limiting ant infestations include:
Eliminating piles of lumber, bricks, or other debris that could serve as a nesting site for ants. Keeping landscaping mulch less than 2 inches thick and at least 12 inches away from foundations. Ensuring the sprinkler system does not spray directly onto the foundation. Sealing as many cracks in the building’s exterior as possible. Keeping tree and shrub branches trimmed to prevent touching the building. Considering re-landscaping to avoid using plants that are prone to aphids and similar insects. At the very least, treat such plants for aphids regularly.