As the weather warms, homeowners may panic if they notice large black ants  most likely carpenter ants  in and around their house, fearing that the home's structural timbers are at risk to the pests. However, even if you have a carpenter ant infestation, you probably have little to worry about.

Although often blamed for causing damage to wood, carpenter ants usually are little more than a nuisance.

Carpenter ants are somewhat lazy. They usually attack wood that's already rotted. If they run into a sound, dry piece of wood, they generally won't go much farther. But they have been known to cause extensive damage to soft materials, such as insulation board.

Carpenter ant workers are wingless, dark brown to black in color and 1/4 to 1/2 inch long. The winged reproductives resemble the workers but are up to 3/4 inch long. The ants' bodies are constricted between the thorax and the abdomen.

Because carpenter ants are social insects that live in colonies and excavate wood, they often are mistaken for termites. However, termite workers are creamy white and live hidden from view. Winged termite reproductives may resemble carpenter ants, but termite bodies are not constricted between the thorax and abdomen. In addition, termites' antennae are straight with bead-like segments, whereas carpenter ant antennae are elbowed.

In nature, carpenter ants aid in the decomposition of dead, decaying trees by excavating rotted wood for nesting sites. They eat dead insects and other small invertebrates as well as honeydew secreted by aphids and scale insects.

When foraging for food, carpenter ants may find their way inside your house. There, they will feed on meats and foods containing sugar and fat. In some cases, these foraging workers may establish a satellite colony in the house, congregating in existing voids, such as hollow doors or the space between studs in walls. 

In homes, the ants typically do not excavate wood for nests. They may tunnel through sound structural timbers, but this has little effect on the timber's structural integrity.

To get rid of the ants, the parent and satellite nests must be found and eliminated:

Use a flashlight to look for foraging workers at night. Check basement, attic, garage and building exterior from May through July between the hours of 10 p.m. and 2 a.m.. It may be possible to find where they're entering the house or follow them back to their parent colony, which often is located in a tree, log or waste wood within 100 yards of the house. If numerous winged reproductive ants are found at windows, they probably came from an indoor nest.

Check areas where the wood may be wet or damp because of poor ventilation, a leaking roof, defective flashing, overflowing or leaking gutters and downspouts, condensation from water pipes, or leaking bathtubs, showers and appliances. Look for piles of coarse, stringy wood particles, dead insect parts and other debris sifting from cracks in the siding, behind moldings, in the basement and attic and under porches. Because carpenter ants don't feed on wood, excavated particles are dumped outside the nest. Satellite colonies within homes sometimes can be located by listening for rustling sounds in walls and ceilings using a stethoscope or inverted water glass.

Remove stumps, logs, and waste wood within 100 yards of the building. Do not allow vegetation, especially evergreen shrubs and trees, to be in contact with the house.

Store firewood away from the house, bringing it into the house only when needed.

Keep wooden parts of the house dry by making needed repairs to roofs, flashing, gutters, and downspouts. Replace any water-damaged, decaying wood. Carpenter ants usually won't infest wood that is sound and has a moisture content of less than 15 percent.

Seal holes through which pipes and wires enter the house.

Spraying insecticide along baseboards and around doors and windows may stop ants from foraging in those areas temporarily. However, because the nests often are in walls, it won't eliminate the problem. Commercial baits aren't very effective for carpenter ants. Your best bet is to spray around the exterior of the foundation, which provides a barrier to ant movement. Sprays should be applied at least once a month from April through September for most areas. Use only products manufactured and approved for this purpose and carefully follow the instructions and precautions on the label. If you prefer to hire professional help to get rid of carpenter ants, first get estimates from at least three reputable pest control companies.