Introduction
Carpenter ants belong to a particular genus of ant that are well known for their ability to damage wooden structures.
The red and black carpenter ant, (Camponotus herculeanus) along with the black carpenter ant (Camponotus pennsylvanicus), are two of the most common types found in Canada. In addition to being a nuisance in homes in their search for food, carpenter ants can also cause structural damage to woodwork as they tunnel through timbers.
The Biology and Lifecycle
Like all ants, carpenter ants are social insects, living in large colonies consisting of hundreds of workers, several reproductive males and females, and one or more queens. The male members exist in the colony only briefly. They die soon after mating, and the fertilized females fly on to new sites where they establish new colonies. During warm weather, eggs are laid that develop into a larval, then a pupal stage over the course of 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.
Carpenter ants vary in length from 6 to 25 mm. Workers are generally 6 to 13 mm long; males range from 9 to 10 mm; females are the largest,varying in length from 12 to 25 mm. The body is divided into three segments, with very slim waists and segmented antennae. 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.
Habitat
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 prefer moist, decaying wood, and their presence in a home can be a sign of a moisture problem, or of wooden structures suffering from decay. Carpenter ants can, on occasion, mine sound wood, but it is usually a soft wood, such as pine or more commonly rotten and soft wood that they
choose. They excavate galleries much longer than those produced by termites. The wood is not eaten but ejected from the nest as sawdust-like shavings.
These have a shredded texture, somewhat like the shavings found in pencil sharpeners. Indeed, heaps of these wood fragments, which the ants have expelled through slits in the infested woodwork, may be one of the signs of infestation.
In addition to tunneling in outside woodwork of buildings, wooden steps and sills, they also infest hollow spaces such as wall voids, attic spaces, hollow doors, cracks, crevices, furniture and existing termite galleries. Nests have also been found behind books in libraries, behind drawers in dressers and cabinets, and in styrofoam insulation.
Food
Carpenter ants are omnivorous insects, eating both plant and animal matter. Insects and small invertebrates (both live and dead), meat products, grease and fat, grains and cereals, as well as a variety of sweets such as syrup, honey, sugar, jelly and fruits provide sustenance for foraging workers. Food is seldom carried back to the nest. Workers usually consume it on the spot, and regurgitate it back at the nest to nourish developing larvae, non-foraging workers and the queen.
Entrance
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 contact 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
There are several obvious signs of infestation such as ants traveling about in search of food, or swarms of winged reproductive ants trying to escape to the outdoors, usually in the spring. Piles of sawdustlike borings expelled from their galleries, slitlike openings in woodwork, faint rustling in walls, floors and woodwork are other common signs.
Detection of Nest
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. A good indicator of the presence of a colony is a high concentration of ants in a particular area, e.g., under the kitchen sink.
Carpenter ant colonies can sometimes be located by sound. An active colony produces a dry rustling noise that can be quite loud. In some instances, when other noises in the house are at a minimum, this rustling can be heard simply by standing in the middle of the room. In other cases, use of a wine glass or stethoscope to listen to the walls will aid in detecting the nest. Most activity occurs at night, as they are night foragers. Following foraging ants to detect patterns in their movement can also help isolate the source of infestation.
Control Measures
Correction of conditions conducive to carpenter ant infestation should be the first step. This includes clearing away any decaying or infested wood from around buildings and removing firewood from inside the premises and away from the sides of buildings. If possible, decaying or infested structural wood should be replaced with sound material. Humidity problems in the home should be investigated and corrected. Removal of potential food sources will discourage ants from entering buildings. This can be accomplished by keeping food in sealed containers and by implementing good sanitary practices such as regularly sweeping up all crumbs and other food fragments.
Chemical control methods have two major goals: elimination of existing nests and prevention of further pest entrance. Chemical control is most effective when used in conjunction with the above methods of physical control. It should be noted, however, that once a colony is well established, it is usually necessary to locate and treat the actual nest site to achieve permanent or long-term control. In difficult instances, this job may best be left to a professional exterminator.
Pesticide Application
Domestic class products for ant control available to homeowners will generally
contain the active ingredient carbaryl or propoxur. The application of such
products as boric acid or diatomaceous earth can be effective in reducing the
number of ants infesting a household. There are also several other commercial
products available to professional Pest Control Operators.
Pest control products should be applied to areas around doors, windows and
other places where ants may enter the premises. Dust or spray ant runways and
hills found in lawns and gardens. Effective control may necessitate locating
and destroying colonies found within 90 metres or so of the house.
Inside the house, force the pesticide product into infested wood through existing
openings or newly drilled small holes. Where possible, locate and
treat nests and surrounding areas. Spray or dust the product into areas where
the ants may hide, including cracks and crevices, along baseboards, behind
and beneath sinks, stoves, refrigerators, cabinets and around garbage cans,
plumbing and other utility installations. Repeat treatment if reinfestation
occurs. Good sanitary practices should be maintained to prevent reinfestation.
For commercial food processing or preparation areas, use products specifically
labeled for such sites. Carefully follow all label directions and
precautions. Remove or cover all food, packaging material, and utensils before
treatment. Afterwards, wash all surfaces that may be in contact with food and
rinse thoroughly with potable water before re-use.
If treatment is being done professionally, occupants and pets should not be
present during application and for sufficient time afterwards to allow thorough
drying of the product and ventilation of the premises.
Note: When applying pesticides, it is advisable to leave any dead ant
carcasses on the floor. Other scavenging ants will either ingest or bring the
dead ant back to the nest to feed the rest of the colony. In this way, the
pesticide’s effect is passed on.
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