Carpenter ants get their name from their habit of hollowing out galleries in wood as nests. They can do serious damage to building when they cut extensively in structural wood. Although carpenter ants do not sting, many are rather large and can cause a painful bit if disturbed.

The first sign of an infestation my be a sighting of several sizeable worker ants crawling along a counter top, or small piles of ragged "saw dust." Each pile of debris is usually directly below a small hole in some wooden part of a cabinet, window sill or structural part of the building. Worker ants push the debris out of their galleries through the small holes. Another common sign, most often seen in Spring, is a swarm of winged reproductives emerging. They may fly to lights and may be confused with termites.

The most widespread species are either black or brownish-red and black, but some species may be all orange-red in color. All species mainly attack wood which is, or has previously been, wet and has already been damaged by fungi.

Even though these ants first invade wet, decayed wood, they soon begin expanding their smooth-walled galleries into sound wood. The main nest is often outside in a rotten log, tree stump or post. Workers often forage as far as 100 meters from the nest. They mainly feed on sweets such as honeydew, plant sap, cereal grains, other insects and even oily or fatty materials. Food scraps and crumbs may be an ant banquet. Carpenter ants usually come into buildings through cracks around doors and windows, or through exterior holes in plumbing, electric wires, TV cables or phone lines. they will also crawl along overhead wire, shrubs or tree limbs that touch the building far above the ground.

Carpenter ants can be hard to control One must first determine whether the ants seen indoors have a nest in the structure or are merely foraging there from outside. It usually requires a trained professional to detect the tell-tale signs of typical carpenter ant debris, gallery openings, foraging trails or typical gallery cutting sounds. A carpenter ant nest can sometimes be detected in a wall by a rustling sound in a void or in the wood, or by gently "sounding" the wood to detect hollowed-out-areas.

If the ants are only foraging from outside, they can be excluded by sealing, caulking or putting down a good physical or chemical barrier. Closing all holes for pipes or wires, and cutting back all trees and shrubs so they don't touch the building can help. If they have established a nest in the wood of a structure, you will probably need the services of pest control professional to help determine and implement an effective plan to control them and prevent reinfestation. This is especially true if any form of chemical control is needed.

© National Pest Management Association