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Carpenter Ants
Carpenter ants in the forest are considered beneficial because they prey on other insects and enhance the decay of stumps and other wood debris. Unfortunately, given favorable conditions, they also attack wood in structures and the interiors of living trees. Ants do not see houses, only dead wood.
Carpenter ants attack wherever excessive moisture accumulates in parts of dwellings, power poles, and fence posts. Especially vulnerable are porches, roofing and areas near kitchens and bathrooms where water is in contact with poles and building foundation timbers. The wood in contact with the ground can absorb large amounts of moisture from the soil and are thus susceptible to ant colonization.
SYMPTOMS: The presence of otherwise unexplained coarse sawdust inside or beside a house, timber pole, or tree usually indicates that carpenter ants are at work. They chew the wood into small fragments, which they discard outside the tunnel, thus forming a "nest" to use as a shelter in which to breed and from which to forage. Their food is varied: They gather sweet secretions from other insects (aphids, etc.) and plants; prey on other living insects; scavenge dead insects; and gather household foods, such as fats, sugar and other sweets. Their need to travel outside their wood tunnels in search of food (foraging trails) often reveals the location and extent of the colony.
DAMAGE: The tunnels or galleries are principally gnawed by the workers and gradually enlarged to accommodate a growing ant colony. These galleries usually follow the soft portions of the wood, parallel to the grain. The inner surfaces of the galleries are clean and appear as if they had been sanded.
Most damage occurs during the warm summer months when carpenter ants are most active. Their out door activity varies with the weather, but usually they are active between the first of May and the end of September. In heated buildings ant activity may continue later in the fall and begin earlier in the spring than is usual with outdoor colonies.
DESCRIPTION: Carpenter ants vary in length from 1/4 inch to more than 1/2 inch. The most common variety is black, although some of the varieties of less importance are partly red. In the early life of the colony, the ants produce wingless workers. After three or more years some of the ants, born with wings as reproductive males and females, swarm and mate. The females attempt to start new colonies.
LIFE CYCLE: Mating takes place in flight during late spring and early summer when winged males and females leave an old colony. The male dies soon after mating and the female, called the queen, locates a nesting place in wood. She then excavates a small chamber in which she secludes herself and lays her first eggs.
When the eggs hatch, the queen nourishes the larvae until they are fully developed. The larvae enter a pupal period within a tan-colored cocoon before becoming adults. Development from egg to adult takes about three months, depending on temperature conditions, during the warmer part of the year.
First-year broods are small, sometimes consisting of only 10 to 20 ants. In following years, colonies often increase to 2,000 to 3,000 ants. It is from these large colonies that winged males and females swarm, mate and start new broods.
PREVENTION: Simple and inexpensive measures to keep wood dry will reduce carpenter ant damage in buildings. It is imperative that moisture be minimized by the following measures:
- Use construction which permits wood to shed water quickly and to dry easily.
- Avoid placing wood in contact with the ground.
- Separate wood from concrete or masonry with a waterproofing compound, such as coal tar or asphalt.
- Provide adequate ventilation in damp areas.
- Provide vapor barriers when insulating outside walls.
- Keep gutters and downspouts clear of debris.
- Inspect regularly to detect and repair leaks in roofing and siding, flashing around chimneys, skylights and gables.
- Also check these danger points: wood porches, steps, columns, corner supports, and wood near "sweaty" plumbing leading to laundry rooms, bathrooms and kitchens where moisture may condense.
- Keep vegetation touching structures to a minimum. Trim back tree branches a least a foot away from the structure.
CONTROL: Carpenter ant colonies in houses may be exterminated by properly injecting a residual insecticide into and around the nest. Effective insecticides are not available to consumers in Canada. Common ”ant traps” and liquid “ant bait” have no effect on this species of ant. Locating and treating the nesting sites cannot be overemphasized. Experienced pest control professionals have a good idea where the nests are likely to be and will be able to detect symptoms that the average homeowner may overlook.
Tracking them will provide good clues. They simply must leave the nest to obtain their food but only a few of the ants do the foraging. More than 90% of the ants NEVER leave the nest so killing ants outside the nest has almost no effect on the colony. Spraying pesticides randomly whenever ants are seen may result in the nest moving or worse yet, spitting into 2 or 3 new nests.
Best Solution: Because of the difficulty in total elimination of carpenter ants and the risk of considerable structural damage, the most effective and least costly solution is usually to call a pest professional.
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