Carpenter Ants

Carpenter Ants - What are they?

Carpenter ants vary in length from 6 to 25 mm. Workers are generally 6 to 13 mm long. The reproductive forms are distinct in size, with males ranging from 9 to 10 mm while females are the largest, varying in length from 12 to 25 mm. The body is divided into three segments, with a very slim waist separating the thorax and abdomen. Their elbowed antennae are segmented. Male and female adults have wings at mating time, and the front wings, if present, are much longer than the hind ones. The red and black carpenter ant has a dark brownish black body, with a reddish brown thorax. The black carpenter ant is uniformly dark brownish black. The red carpenter ant and the black carpenter ant are two of the most common types found in Canada.
All ants undergo complete metamorphosis, so their nest may contain eggs, larvae and pupae as well as adults. Carpenter ants live in large colonies consisting of hundreds of workers, all sterile females, several reproductive males and females, and one or more queen. The male members exist in the colony only briefly, dying soon after mating, and the fertilized females fly on to new sites where they establish new colonies. During warm weather, eggs are laid and develop through all stages in about 66 days (under optimum conditions). The workers are responsible for caring for the young and foraging for food to feed the rest of the colony.

When part of an established colony wanders into a nearby structure, it sometimes establishes a smaller satellite colony there. Some experts actually consider this as the main mechanism for house invasions by carpenter ants.
Carpenter ants eat both plant and animal matter. Their natural food sources consist of insects and other small invertebrates, and sweet exudates from aphids and other insects. Protein and sweet foods found in and around homes also provide sustenance for foraging workers. Workers will consume food on the spot, and regurgitate it back at the nest to nourish developing larvae, non-foraging workers and the queen.

What Can They Do?

Carpenter ants construct nests by burrowing into wood. Outdoors, they are found in dead trunks of standing trees, stumps, or logs, or under fallen logs and stones. They can, on occasion, mine sound wood, but usually choose a soft wood, such as pine. Because of their preference for moist, decaying wood, their presence in a home can signal a moisture problem, or wooden structures suffering from decay. These ants excavate galleries much longer than those produced by termites.

The wood is not eaten but ejected from the nest as sawdust-like shavings. In addition to tunnelling in the trim of buildings, wooden steps and sills, colonies can nest in houses without attacking structural timbers, using hollow spaces such as wall voids, attic spaces, hollow doors, and can even be found behind books in libraries, behind drawers in dressers and cabinets, and in styrofoam insulation.

How Can I Manage Them?

A thorough inspection of areas of high moisture, wood in contact with the soil, areas of improper ventilation, and exposed structural lumber is the first step. Carpenter ants get into houses in several ways: through windows, holes in foundations, heating ducts and air-conditioners, along power or telephone cables, points where tree branches or other vegetation come in contact with the house, or via wooden structures attached to houses, such as porches and sheds. Firewood brought into the house can also be a source of carpenter ants.

Signs of Infestation

Determine if there is actually an infestation of carpenter ants or if it is a case of individual ants wandering in the house. Look for a high concentration of ants in a particular area like under the kitchen sink.
Pay attention to foraging ants and the patterns of their movement. For example, there may be a trail communicating with a parent colony outside. Note: they are most active after sunset.
Notice if there are swarms of winged reproductive ants trying to escape to the outdoors, usually in the spring.
Look for piles of sawdust-like borings expelled from their galleries and slit-like openings in woodwork.
Listen for the sound of an active colony which will produce a dry rustling noise that can be heard best at night during high ant activity and quiet time in the house. The use of a wine glass or stethoscope can be helpful to listen to the walls.

Physical Control

Clear away any decaying or infested wood from around buildings and remove firewood from inside the premises and away from the sides of buildings. Do not bury stumps or other wood debris in proximity of the house. Pay attention to the state of landscaping elements such as decorative bark, retaining walls and driftwood. Humidity problems in the home should be investigated and corrected. Decaying or infested structural wood should be replaced with sound material. Removal of food sources will discourage ants from invading buildings. Keep food in sealed containers and regularly sweep up all crumbs and other food fragments. Good sanitation should also prevent re-infestation.