Fact sheet Ant Management in Turfgrass Introduction

FS013
Fact sheet
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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).
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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
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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
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RUTGERS, THE STATE UNIVERSITY OF NEW JERSEY
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