Provided by Insects in the City, Dr. Mike Merchant, Extension Urban Entomologist
Photos: Male (left) and
female carpenter ant swarmers.
Note the pinched waist that distinguishes these
insects from termites.
Many social insects periodically do
something called “swarming”. Swarming occurs when reproductively mature,
but unmated, kings and queens leave the nest to mate. These mating
couples are winged and are referred to as alates, or swarmers. The
earliest swarmers to emerge in the winter are carpenter ants.
This week my youngest daughter, home
for the weekend for a visit, informed her entomologist dad that the upstairs
shower was covered with large ants. A quick inspection confirmed that we
were being invaded by carpenter ants. A few years ago we remodeled this
particular shower, tearing out sheet rock and insulation and encountered
carpenter ants living in the surrounding walls. We throughly cleaned out
what we could and sprayed the walls down with a residual insecticide before
reinstalling insulation and more water-resistant Hardyboard® in the new shower
stall. Apparently they are back.
Carpenter ants are relatively large
for ants, 1/4 to 1/2 inch-long. They may come in different colors, but
are usually red or black, or a mixture of the two colors (see pictures).
They may or may not have wings. In my home I only spotted the
wingless worker ants, but I suspect the swarmers will show up soon.
Dozens, even hundreds of swarmers may emerge from an indoor carpenter ant
nest.
In some parts of the U.S. carpenter
ants are important wood-destroying pests–not something that any homeowner wants
to see in their house. But here in Texas our carpenter ants are a little
less threatening. They certainly can be a nuisance through their
presence, and for the little piles of debris they often deposit on windowsills
and floor near their nests. But they do not do significant damage to 2×4
studs or other structural wood.
Unfortunately, carpenter ants are
always difficult to treat and eliminate completely from the home. For my
part I plan to inject an insecticide into the gap in the shower grouting from
which they obviously emerged, reseal the grout and not lose much sleep over the
incident.
If you discover carpenter ants in
your home, look for the hole where they are emerging. This may or may not
mark the exact location of the nest, but it will be close. For most
people, calling a professional is the best option for control. If you
choose to try the DIY route, you can either seal up the hole and do nothing, or
attempt to treat the hole with an aerosol insecticide labeled for use indoors
against ants and then seal the hole. You may be fortunate, and eliminate
the colony in this way, or you may eventually have to resort to professional
assistance. In any case, doing nothing to the ants will not likely result
in any serious damage to the home…just some nuisance ants emerging from time to
time.
For more information about these
ants, see publication E-2001 on
carpenter ants, or the publication on swarming insects
indoors, Ent-2012.
