Turfgrass Entomology (ants)



ant photo ant mound photo ant mounds photo


Ants (Family Formicidae) are social insects which build their nests in soil, wood or other suitable substrates. They occasionally become a problem in turf when they invade lawns, parks, golf courses, playgrounds, cemeteries and other turfgrass areas. Ant mounds can be particularly troublesome on golf greens and fairways where maintaining a uniform playing surface is essential.
Description and Life History
A typical ant colony consists of an egg-laying queen, males, immatures (eggs, larvae and pupae) and hundreds to thousands of sterile female workers which can become a nuisance as they forage around buildings, sidewalks, foundations and driveways. Ants consume a wide variety of foods including seeds, small insects, plant sap, flower nectar and fungal growth. Many ant species feed on honeydew, a sweet liquid secreted by plant-feeding insects such as aphids, mealybugs, scale insects and leafhoppers. In the spring and fall, colonies produce winged ants that leave the colony, mate and seek new nesting sites.
General Symptoms of Ant Damage to Turfgrass
Ants normally establish their colonies in sunny locations in well-drained soils. In turf, a nest consists of a series of underground tunnels and galleries which may extend three or more feet beneath the soil surface. Multiple openings provide access to the surface. During nest construction, ants excavate large quantities of soil which they deposit in mounds on the surface. Not only are these mounds unsightly, but they can smother the turfgrass immediately surrounding colony openings and make routine maintenance difficult by producing a bumpy, uneven turf. Beneath the surface, soil excavations allow grass roots to dry, which can injure the turf stand. In addition, some ant species such as yellow ants and cornfield ants nurture colonies of root-feeding aphids which they "milk" for their honeydew. These aphids can further stress the turf by withdrawing sap from the roots and underground stems. In newly-seeded areas, ants occasionally become a problem when they collect seeds and carry them back to the colony for later consumption.
Sampling Techniques
Ants are best detected by inspecting turf areas for mounds and worker ant activity. They also can be detected by sprinkling 1/4 cup of lemon-scented household detergent mixed in two gallons of water over one square yard of turf and observing the insects as they move to the surface.
Management Strategies
Effective ant control normally requires destruction of the queen. In most cases, this necessitates one or more applications of a liquid or granular insecticide. In situations where only a few colonies are present, apply insecticides directly to colony openings and the areas immediately surrounding the mounds. If colonies are numerous, broadcast treatments over the entire infested area may be the most practical solution. When liquid insecticides are used, apply sufficient spray volume to ensure thorough wetting of the soil surface. For granular applications, irrigate thoroughly after treatment to activate granules and move the insecticide down into the soil profile. In most cases, a single insecticide application will provide acceptable ant control for the season. Additional treatments may be needed if the queen was not eliminated or if ants recolonize the treated area. In addition to standard liquid and granular insecticides there are several bait formulations that can be placed in areas where worker activity is observed.