FS013 Fact sheet For a comprehensive list of our publications visit www.rce.rutgers.edu Ant Management in Turfgrass Albrecht M. Koppenhofer, Ph.D., Extension Specialist in Turfgrass Entomology Introduction Several species of ants commonly inhabit home lawns, golf courses, and other turf areas. Generally, ants are beneficial scavengers or predators of eggs, larvae, and adults of many turfgrass insect pests, and help suppress pest outbreaks. In some habitats ants can move as much soil as earthworms, reducing soil compaction and moving organic matter into the soil. Therefore, controlling ants in turf is not recommended unless their nests occur on golf putting greens or other sensitive areas. Some ant species can inflict painful stings when their colonies are disturbed, particularly fire ants and harvester ants. But these species occur only in southern and western states. This fact sheet is written for conditions and species in the Northeast, with emphasis on the turfgrass ant. Symptoms Several ant species can become a nuisance in turf areas when they nest and construct small volcano-shaped mounds around the openings of their underground nest. They generally seek out drier, well-drained soils with low water-holding capacity. The galleries they build may damage roots and add to desiccation of the soil, and the surrounding turf can become thin and unsightly. Some ant species nurture colonies of root-feeding aphids, which they “milk” for their sugary excrements (‘honeydew’). These aphids can further stress the turf by withdrawing sap from the roots and underground stems. In newly seeded areas, ants can become a problem when they collect seeds and carry them back to the colony for later consumption. On home lawns and in similar turfgrass settings, ants rarely cause serious damage. But on the short-cut grass of golf course greens, tees, and fairways, their mounds dull mower blades and smother the surrounding short grass. Insect Description Ants (Family Formicidae) belong to the order Hymenoptera along with bees and wasps. Adult ants have a constricted waist, elbowed antennae, and typically range in length from 1/16” to 3/8” (1.5 to 10 mm) (Fig. 2). The body surface may be smooth, hairy, black, brown, red, or light tan. Ants can be wingless or may have two pairs of wings. The front wings are much larger and longer than the hind wings. Swarming winged ants may be mistaken for reproductive termites, causing concern in homeowners. But winged termites have a black body, a broad waist, straight, beadlike antennae, and front and back wings of equal size and shape (Fig. 1). Fig. 1. Comparison of winged ant and termite (University of Kentucky Cooperative Extension Service). Ant eggs are tiny, white or cream colored, and vary in shape among different ant species. The maggot-like ant larvae are legless with transparent whitish soft bodies and a light colored head. Ant pupae are small and translucent, with the structures of the adult ant visible but closely appressed to the body. In some species the pupae are enclosed in tough, papery, and yellow to tan cocoons. Pupae are often mistaken for eggs when nests are dug up. Each colony has one queen. Individual queens and colonies may persist for several years. Established and new colonies that have survived the winter resume activity in late April to early May. New adult workers begin to appear in July, and mound proliferation increases dramatically. Swarming occurs in late summer or early fall and is usually synchronized over large regions. Turfgrass ants feed on dead insects, insect eggs and small insects, earthworms, and any other acceptable food. They also tend subterranean root aphids to feed on their honeydew. Seasonal History and Habits In most turf settings, the turfgrass ant is beneficial because it is a voracious predator of eggs and small larvae of white grubs, sod webworms, and cutworms. However, in the short-cut grass of golf greens, tees, and fairways these mounds disturb ball roll, smother the surrounding grass especially when compacted by mowing or foot traffic, clog machinery, and dull mower blades. On putting greens and tees with high sand content, more than ten nests per square yard can exist. Ants live in colonies that consist of hundreds to thousands of individuals. Most of the ants are workers sterile, wingless females that do all the work including foraging for food, constructing and defending the nest, and tending to the queen and the young. Most ant species have one reproductive female, the queen, per nest, but some species can have multiple queens. The queen lays all the eggs, from which the colony reproduces. In mature colonies (2 to 3 years or older), some of the offspring develops into winged males and females. At certain times during the year (usually early spring or late summer depending on species), these winged forms leave the nest in a swarm and mate. The males die soon afterwards while the mated females disperse. Upon finding a suitable nesting site, the young queens start new colonies. Important ant species in turfgrass (Fig. 2) The turfgrass ant (Lasius neoniger) is the most common ant on golf courses over most of the United States but is also common in other sunny turf areas. The workers are brown and approximately 1/8” (3 mm) long. Its nest consists of shallow interconnected chambers concentrated in the upper 12” (30.5 cm) of soil, with some vertical galleries going as deep as 3 feet (91.5 cm). Each colony has multiple subdivisions and several entrances. Each entrance is surrounded by a craterlike ring of excavated soil, typically 1” to 2.5” (25 to 63 mm) in diameter and 0.6” to 1” (15 to 20 mm) tall. The mounds can measure up to 5” (125 mm) in diameter and up to 1.5” (40 mm) in height. Fig. 2. From top to bottom: turfgrass ant, little black ant, pavement ant, larger yellow ant (from Smith 1947). 2 share food by regurgitating it and passing it on to other colony members. The following are some other ant species common in lawns. Workers of the little black ant (Monomorium minimum) have soft jet-black bodies and are 1/10” to 1/8” (2.5 to 3 mm) long. These ants are found primarily in soil and rotting wood, and feed on a wide variety of food sources. Workers of the pavement ant (Tetramorium caespitum) are slow, sluggish, shortlegged, brownish-black and 1/12” to 1/4” (2 to 6 mm) long. This species usually nests under pavements and foundations and feeds on a wide variety of foods including seeds, grease, and animal food. Workers of the cornfield ant (Lasius alienus) are robust, softbodied, light to dark brown, and 1/8” to 1/4” (3 to 6 mm) long. When crushed they smell of formic acid. This species usually nests in open places in the soil or in rotten wood, but sometimes also on golf greens. It feeds on seed and honeydew from aphids and mealybugs. Workers of the larger yellow ant (Acanthomyops interjectus) are yellow and 1/10” to 1/ 8” (2.5 to 3 mm) long. When crushed they give off a lemon-verbena odor. This species nests in soil and tends mealybugs and aphids on plant roots to feed on their honeydew. If only a few mounds are present, spot treatment with bait formulated products are most effective. Apply baits to the area directly surrounding the mounds. Because bait effectiveness relies heavily on bait retrieval and sharing within the nest, the bait’s particle size and attractants must match the foraging behavior and nutritional demands of the target species. Some species prefer protein based baits, others carbohydrate based baits. In addition, the nutritional demands can change during the season. Compounds based on baits include abamectin B1 [Advance® Granular Ant Bait (soybean oil and corn grit carrier), Advance® Granular Carpenter Ant Bait (soybean oil and corn grit carrier plus meat meal and sugar)], hydramethylnon [Maxforce® Professional Insect Control Ant Killer Granular Bait (granular protein carrier)], and fipronil (Chipco® Firestar Fire Ant Bait). Against the turfgrass ant, Advance® Granular Carpenter Ant Bait appears to be the most effective bait followed by Maxforce®. However, on putting greens Maxforce® is less conspicuous due to the smaller size and darker color of its granules compared to carpenter ant bait granules. Because turfgrass ant workers forage around the clock baits can be applied any time. However, avoid wet grass and withhold irrigation for at least 8 hours after treatment because baits that become wet lose attractiveness. Management/Control Ant control products can be applied as sprays, granules, or formulated on baits. Either approach generally works best in early spring, probably because the colonies are weakened following overwintering and newly started colonies are still very small. For all products, repeated applications at monthly intervals may be necessary in widespread or difficult situations. Sprays/granules For the control products, active ingredients listed below are followed by the trade names in parentheses. Be aware that active ingredients in these products may change. When purchasing control products, always check the label for the active ingredient. Always read instructions on insecticide labels very carefully. If there are numerous colonies spread over a large area, it may be more practical to make liquid or granular insecticide applications over the entire infested area. While baits can also be broadcast, their effectiveness appears to be lower with this approach, and the cost of application may become too high. However, insecticides presently available for ant control in liquid or granular formulations kill the worker ants too quickly to allow the compounds to spread through the colony and kill the queen(s). Thus, they provide only temporary mound suppression. Applications in spring within 1 week of mound appearance may provide 4 to 6 weeks of mound suppression, later applications only 2 to 3 weeks suppression. Ant Baits The key to eliminating ant colonies is to kill the queen(s). This can be best achieved with delayed action compounds formulated on baits that are picked up by foraging ants and brought into the nest. The compound will spread through the nest because ants 3 Non-bait based insecticides labeled for ant control include bifenthrin (Talstar®, Ortho® Lawn Insect Killer Granules), carbaryl (Sevin®), chlorpyrifos (Dursban®; not for residential turf or where children may be exposed; restricted use), cyfluthrin (Tempo®), deltamethrin (Deltagard ® ), lambda-cyhalothrin (Battle®, Scimitar®), or permethrin (Astro®). Note that chlorpyrifos, deltamethrin, and lambda-cyhalothrin are available only for commercial use. Granular insecticides (but not baits!) need to be activated and moved in the soil with some irrigation (about 1/8” = 3 mm). Liquid applications require enough spray volume (or post-treatment irrigation) to thoroughly wet the soil surface. The material can be applied in a gentle rain or just before a predicted rainfall. Rotate materials of different chemical classes to reduce chances for resistance development or enhanced microbial degradation. Always read instructions on an insecticide label very carefully. Note: Because most ants are beneficial predators, controlling them in turf is not recommended unless their nests occur on golf putting greens or other sensitive areas. Mention or display of a trademark, proprietary product, or firm in text or figures does not constitute an endorsement by Rutgers Cooperative Extension and does not imply approval to the exclusion of other suitable products or firms. © 2004 by Rutgers Cooperative Research & Extension, NJAES, Rutgers, The State University of New Jersey. Desktop publishing by Rutgers-Cook College Resource Center Published: November 2003 RUTGERS COOPERATIVE RESEARCH & EXTENSION N.J. AGRICULTURAL EXPERIMENT STATION RUTGERS, THE STATE UNIVERSITY OF NEW JERSEY NEW BRUNSWICK Distributed in cooperation with U.S. Department of Agriculture in furtherance of the Acts of Congress on May 8 and June 30, 1914. Rutgers Cooperative Extension works in agriculture, family and community health sciences, and 4-H youth development. Dr. Karyn Malinowski, Director of Extension. Rutgers Cooperative Research & Extension provides information and educational services to all people without regard to race, color, national origin, gender, religion, age, disability, political beliefs, sexual orientation, or marital or family status. (Not all prohibited bases apply to all programs.) Rutgers Cooperative Research & Extension is an Equal Opportunity Program Provider and Employer.