Do I need a professional for carpenter ants?

You often do not need one. Carpenter ants rarely cause significant structural damage to buildings themselves, but their presence indicates water damage somewhere in the building.^[1] If you can find where they are coming from, fix the damp wood and bait the foragers, you may be able to handle it yourself. A licensed pest control company earns its fee when the nest is hidden inside the house and cannot be reached.

Make sure they are carpenter ants

Carpenter ants vary from about 1/4 inch for a worker to 3/4 inch for a queen, and are black, reddish-brown, or sometimes red and black, with a distinctly pinched waist.^[1] Winged carpenter ants are often mistaken for termites, but carpenter ants have sharply bent (elbowed) antennae while termite antennae are straight.^[3] If you are not sure, read the signs of termites in a house before you pay for anything, because termites call for a different treatment. Subterranean termites build flattened, muddy-looking tubes, most about the width of a pencil, running from the soil to the wood they feed on.^[7]

Carpenter ants do not eat wood; they chew it out to make nests and push the shavings out in sawdust-like piles, and they feed on sweet foods, pet food and other insects.^[1][3]

When you can probably handle it yourself

The season tells you a lot. When carpenter ants are active indoors in late winter or early spring (February and March), the nest is probably inside the house.^[1] Large numbers suddenly seen indoors in late spring may be foragers from an outdoor nest rather than a sign of a nest inside.^[1]

Successful control of indoor carpenter ants requires finding the nest.^[1] Carpenter ants are most active at night, which is the best time to follow their trails and look for sawdust piles.^[3] If the trail leads outside to a stump, a woodpile or a hollow tree, the fix is mostly outdoors.

If the nest cannot be located or exposed, baiting is the most effective means of carpenter ant control.^[2] Boric acid baits labeled for carpenter ants can significantly reduce the foraging population.^[2] Pair the bait with the outdoor clean-up: store firewood several feet away from buildings and off the ground,^[3] remove vines, shrubs and tree branches touching the house,^[1] and remove rotting stumps, logs and other decaying wood near the house.^[1]

If you suspect carpenter ants are nesting in a tree near the house or a walkway, consider having an arborist check the tree, because large numbers of carpenter ants on a tree suggest decay.^[1]

When a professional is worth it

Inside a house, carpenter ants nest where wood has stayed wet: in porch pillars, roofs, windowsills and door frames where water has damaged the wood, in wood touching the soil, around eaves, chimneys and skylights, and in wet foam insulation.^[1] Nests in structural wood are often in moist areas like basements and crawl spaces.^[2] Many of those spots are inside walls or overhead, where a homeowner cannot see or reach them.

A professional brings three things a homeowner usually does not have:

• Better bait. The most specific and effective carpenter ant baits are available only from a professional pest control operator.^[2]
• Direct nest treatment. If the nest is found and can be exposed with minimal damage to the structure, insecticide sprays can be used to destroy the colony.^[2]
• Equipment for a perimeter treatment. A perimeter spray around the base of the house should be applied by a pest-management professional with the proper equipment, in early spring when ant populations are low.^[2]

The treatment is only half the job. Address the causes of the moisture damage and, if need be, remove the damaged wood, or the nest site will remain attractive to other carpenter ants.^[1] That repair usually goes to a carpenter or general contractor. Under Virginia's contractor definitions, someone who repairs a building on a single contract or project worth over $1,000 but less than $30,000 is a Class C contractor,^[8] so check the licence on larger repairs.

How to hire well

In Virginia, no one may apply or recommend a pesticide commercially without a pesticide business license and a certified commercial applicator responsible for the safe application.^[6] Whether pest control companies need a licence in Virginia shows how to check one. Then ask:

• Can the employees identify the pest, explain the extent of the infestation and discuss the products they plan to use?^[4]
• Are they willing to discuss low-toxicity options, and do they have insurance to cover you, your property and their employees?^[4]
• Will they show you where the nest is, or where they think it is, and the wet wood that drew the ants?

The company should inspect and outline a recommended control program, including the active ingredients, how they will be applied, non-chemical alternatives and steps to prevent the problem in future.^[5] What ant control costs in Virginia explains what goes into the price.

Stop and call a pro if

• You see carpenter ants indoors in February or March, or find sawdust-like piles inside the house.
• The trail disappears into a wall, ceiling, floor or window frame you cannot open.
• A few weeks of baiting and clean-up have not reduced the ants.
• Wood near the nest feels soft, or the damp spot is in the roof, around a chimney or skylight, or in the framing. That is work for a roofer or contractor, not a ladder and a can of spray. Whether carpenter ants are a sign of water damage covers where to look.

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