by
Vince Palmere
Ants are now the number one household pest in the United States,
leaving cockroaches well behind. Although there are more than 20 species
of ants that are regular pests in buildings, only a few of them
establish colonies indoors. Ants foraging for food and water indoors are
usually workers from colonies that are located outdoors. Their nests are
in the soil around the perimeter of the house or the yard.
The pest status of ants is based primarily on their presence indoors.
However, carpenter ants have the added impact of being capable of
causing structural damage. These wood-nesting ants are one of the most
common household pests, especially in northern regions.
Carpenter ants are distributed worldwide, from tropical jungles to
cold, north temperate regions. The common name comes from the habits of
a few species that excavate wood to make their nests.
Life Cycle
During the winter, carpenter ant colonies usually contain a small number
of larvae and a large number of workers and winged adults (which may be
as much as 30 percent of the colony). Mating flights of the adults take
place on warm, still days in June and July. After mating, the young
queen sheds her wings and establishes a small nest in cavity of a log or
stump.
The colony grows slowly for the first two years, but within five
years it may contain 3,000 to 6,000 workers. When a colony reaches this
size, it is capable of releasing swarms of winged adults. It will
continue to do so on an annual basis until the queen dies. It is the
presence of swarming ants or the activity of worker ants indoors in
early spring that alert homeowners of a potential infestation.
Seasonal Activity
April and May
In the spring, there is a considerable amount of foraging. The colony
has spent the winter with little or no food, and there is a great need
to replenish the energy reserves of the workers and adults. Basically,
they are hungry and looking for food!
Indoor colonies usually begin foraging in kitchens in February and
March. Eggs and larvae are produced in these colonies in January. Ants
from outdoor nests are limited by temperature - they are not active
until the ground temperature is above 50 degrees Fahrenheit. Periods of
rain in the spring may lead to increased activity indoors.
June
In northern regions, peak foraging occurs in June. In southern regions,
the peak is in July. By this time, there are many aphids on shrubs and
trees around houses or commercial buildings. There are larvae in the
colony at this time, and the foraging workers can take advantage of the
available honeydew.
Increased temperatures in June influence foraging so that carpenter
ants are most active in the morning (from sunrise until about noon),
then again in the evening from sunset until about midnight. In late
June, temperatures may be high. There is little or no foraging when the
ground temperature gets above 88 degrees Fahrenheit.
July
Foraging continues at high levels during the early part of the month,
because the larvae in the colony are growing and need to be fed. High
ground temperatures during this month usually limits foraging to early
morning.
September and October
There is further decline in foraging activity during this time, as the
colony prepares for winter. Most foraging stops when ground temperatures
drop below 50 F.
November through March
The colony is relatively inactive. It is composed of workers that have
built up their food reserves during the late summer, which they will
rely on to get through the winter.
Outdoor colonies will become inactivated by cold temperatures, but
thanks to a built-in antifreeze, the ants can survive low temperatures.
Winged ants are usually present in the colony and more will develop in
the spring. They are ready for the first opportunity in the spring to
leave the colony in a mating swarm - and start the process all over
again.
Dr.William
Robinson. Urban Pest Control Research and Consulting, Christianburg, Va.
Solution
