Carpenter ants are a common sight around Texas homes throughout
the year. Although their natural nesting sites are in trees,
carpenter ants can also invade and live indoors. Texas carpenter
ant species are not usually destructive to homes, however
they can become a nuisance.
Carpenter ants are often first noticed in late winter and
early spring. This is the time when carpenter ants and other
ants emerge to mate and attempt to start new colonies. These
reproductive forms are identified by their two pairs of wings
and relatively large size. The presence of winged ants indoors
generally means that a nest is located in the structure.
IDENTIFICATION
Carpenter ants are among the larger ants found in
Texas homes and yards. There are 18 recorded species of carpenter
ants in the state. The most common indoor species is 1/4-3/8
inch-long with a black tail (abdomen) and reddish-brown head
and thorax. Winged forms of this ant may be entirely black.
Workers of other Texas carpenter ant species range in color
from yellow to black. Other key distinguishing characters of
these ants include a pinched waist, elbowed antennae (these
characters easily distinguish ants from termites), a single
bump or node between the abdomen and thorax, and an evenly rounded
thorax when viewed from the side with a hand lens.
Carpenter ant reproductives are winged, sexually mature ants
that range in size from 1/4-1/2 inch-long. Hundreds of reproductive
males and females may appear in a home over a several day
period as the swarmers emerge for mating.
DAMAGE
Carpenter ants do not eat wood, and generally are
not as damaging as termites. Carpenter ants use narrow, protected
void areas for nests and may be found in doors, window frames,
and walls. Southern carpenter ant species prefer to nest in
existing voids and cavities and do not usually excavate large
nests in wood. For this reason, and because they tend to have
smaller colonies, Texas carpenter ants are not as destructive
as species found in the northwest and northeastern regions
of the United States. At worst, carpenter ants may, on occasion,
cause minor damage to isolated pieces of wood. Because carpenter
ants are classified as wood-destroying insects, however, they
are reportable on real estate transactions and can affect
the resale value of a home.
CONTROL
Carpenter ant control can be difficult. The surest way to eliminate
a carpenter ant infestation is to locate and treat the nest,
or nests. Carpenter ants make their homes in a variety of sites
including solid wood, hollow core doors, window and door frames,
hollow walls, insulation, cardboard boxes, etc. Although carpenter
ants can bore into sound, dry wood, they prefer using existing
cavities or excavating softer materials, especially near a moisture
source.
Carpenter ant nests can sometimes be located by the presence
of small piles of sawdust, or frass. This frass consists of
wood shavings or other material excavated from the ant's nests,
as well as tiny fragments of dead ants and other insects.
The presence of frass is a good sign that a nest is nearby.
Carpenter ant frass is usually pushed out of a small hole
in the nest chamber. If you can find such a hole, it frequently
leads directly into the nest chamber.
Once a nest is located, it can be treated with an insecticide
dust labeled for use in wall voids of homes. Pest control
operators typically use insecticide dusts containing deltamethrin
(DeltaDust®), cyfluthrin (Tempo® Dust)
or carbaryl (Sevin®), or injectable aerosol sprays,
when treating suspect wall voids or other nest sites. Such
treatments can generally be made very safely with little or
no chance of exposing residents to pesticides.
Should you attempt carpenter ant control yourself?
Although do-it-yourself drilling and treating walls is possible,
an easier approach is the use of baits. Carpenter ants have
traditionally been difficult to lure with baits, however some
new products may be worth trying. Whitmire Granular Carpenter
Ant Bait, Maxforce® Carpenter Ant Gel, and Maxforce®
Outdoor Ant Killer Granules have been used successfully against
carpenter ants. These products should be placed outdoors along
carpenter ant foraging trails. Containerized ant baits often
include label recommendations for indoor use against carpenter
ants, however they have had little reported success against
our Texas species. Commercial boric acid baits using peanut
butter, molasses or jelly as an attractant may control some
colonies. Baits with lower percentages of boric acid (1-2%)
appear to work best. Fire ant baits are unattractive to carpenter
ants.
Baits should be placed near ant trails or
wherever carpenter ants are seen. The best way to locate outdoor
foraging trails is to use a flashlight at night in warm weather,
when the ants are most active. Trails will be found along
fences or tree branches, wires, etc. Once picked up by ants,
baits are transported to the colony where they are shared
with the queen and other ants. If one bait seems unattractive
when first offered, try it again in another month. Carpenter
ants go through seasonal changes in their food preferences--
preferring sweets at times, and proteins at other times. Do
not use other pesticides near sites where you are baiting,
as this may repel the ants.
FOR
MORE INFORMATION
For more information on carpenter ants and their control,
request publication L-1783, Carpenter Ants, or L-2061
House-Infesting
Ants and their Management.
Author:
Michael Merchant, Ph.D., Urban Entomologist, Texas Agricultural
Extension Service
Publication information:
This publication is part of the House & Landscape Pest
Series produced by the Department of Entomology, Texas A&M
University, College Station, TX 77843-2475. Series Editor:
M. Merchant. For more information about arthropods, check
out the Texas A&M Entomology Website at http://insects.tamu.edu
Last Revised: 06/26/2003
The information given herein is for
educational purposes only. Reference to commercial products
or trade names is made with the understanding that no discrimination
is intended and no endorsement by the Texas AgriLife Extension
Service is implied. Additional, or updated copies of this
fact sheet may be obtained by contacting the author(s) at
Texas AgriLife Extension, 17360 Coit Road, Dallas, Texas
75252-6599. Extension programs serve people of all ages regardless
of socioeconomic level, race, color, sex, religion, disability
or national origin. The Texas A&M University System, U.S.
Department of Agriculture, and the County Commissioners Courts
of Texas Cooperating.
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2003, Texas AgriLife Extension, unless otherwise noted.
All rights reserved.
