The Black Carpenter Ant
The black carpenter ant Camponotus modoc
Wheeler is the common western species. These ants get their common name
from their habit of hollowing out galleries in pieces of wood for nesting
purposes. This nesting habit can result in structural damage. Carpenter
ants are found throughout the United States.
Biology
Black carpenter ant colonies are of moderate size, usually containing
over 3,000 workers (up to 10-15,000 including satellite nests) when maturity
is reached in about 3 to 6 years. The typical western carpenter ant (C.
modoc) mature colony contains about 10-20,000 workers, with large colonies
having up to 100,000 workers.
Habits
Most carpenter ant species establish their first nest in decayed
wood and later expand or enlarge this into sound wood. Inside, nests are
located in wood (preferably softened by fungus rot), in insulation, and/or
in wall voids. Workers are a nuisance when out searching for food but are
destructive to timbers utilized for nesting activities. Outside, nests
are typically located in rotting fence posts, stumps, old firewood, dead
portions of standing trees, and under stones or fallen logs.
The presence of a carpenter ant nest is sometimes indicated by a
rustling sound coming from wall voids or from wood where the colony is
located. Otherwise, the emergence of swarmers indoors may be the first
indication of an indoor colony.
Carpenter ants feed primarily on insect honeydew, plant and fruit
juices, insects, and other arthropods. Inside, they will also feed on sweets,
eggs, meats, cakes, and grease.The workers forage for distances of up to
300 feet (91.4m) from the nest. They typically enter buildings around door
and window frames, eaves, plumbing and utility lines, and shrub and tree
branches in contact with the building.
Although some workers are active during the day, most activity is
from dusk till dawn, with peak activity between 10 pm and 2 am. The trail
between the parent and satellite nest is usually about 1/4-13/16" (6-20
mm) wide and is kept clear of vegetation and debris. It usually follows
contours but typically will cut across lawns.
Control
The first step is to determine if the ants present are merely foraging
inside or if there is a nest inside. The best indication of a nest is the
presence of sawdust piles containing insect body parts. Another indication
is the sound produced as the workers remove wood to expand the nest.
Outside, check around the building's perimeter for foraging trails,
especially in the direction of trees and shrubs; easiest to locate between
sunset and sunrise when the ants are most active.
The second step is to locate any inside nests. Look for sawdust piles
with insect body parts. Listen for ant sounds mentioned above; listening
devices are helpful. Gently tap with a screwdriver, etc. all exposed wood
such as floor joists, sill plates, roof rafters, etc. and listen for sound
changes; nest cavities give a hollow or dull ring. Check suspicious areas
with a knife blade which will readily penetrate infested wood. Be sure
to check crawl spaces, basements, and attics. Carpenter ants have a network
of trails they follow throughout a structure and often use the tops of
electrical Wires and water pipes, so be sure to check where these are.
A moisture meter can be helpful in locating areas of higher moisture in
which the ants prefer to locate their initial nests.
The third step is to determine if the inside colony is a parent or
satellite colony. Inspect and search. Detection of a trail directs one
to the parent colony. For effective control, it is imperative to locate
and eliminate the parent colony.
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Mark Pierce
Oregon Certified Home Inspector
503-757-7784
OCHI #345-PCO
#153495 WSDA WDO #61752
