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Carpenter Ants

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Carpenter Ants

There are many different kinds of carpenter ants. The two that most commonly nest inside houses are large, heavy-bodied ants. Worker ants are wingless and range in size from about 6 mm to 10 mm long. The worker ants of one species are black (Camponotus modoc). These are the ants that can cause significant damage to wood. The workers of the other species have black heads and abdomens (tail-ends) and reddish thoraxes (middle-part) (Camponotus vicinus). They normally are found in cavities or spaces such as between insulation and wood.

Unmated queens and male ants have wings. The queens are about 20 mm long, including their wings, while the males are about 11 mm long.


Thousands of carpenter ants live together in a colony. Each colony has one or possibly a few queens which do all the egg-laying. The queens live in damp wood such as a stump or where there is a leak in a house.

Worker ants gather food, raise the young and hollow out wood to expand the nest. They may live in the damp wood with the queen, or they may take some of the developing young and move to a dry location. A nest of carpenter ants which develops in a separate location from where the queen lives is known as a satellite nest. 75% of carpenter ant infestations in homes have between 1 and 3 of these satellite nests.

Winged reproductive males and females only develop in large, well-established colonies. They may develop in either the main nest or in a satellite nest.


Carpenter ants eat a wide variety of things. A large part of their diet is other insects and honeydew from aphids that they find on trees and shrubs. They also will eat dead animals, sweet materials from plants, humming bird nectar and many things they find in kitchens. Carpenter ants do not eat wood.

Signs of an Infestation in a Home

Carpenter ants may first be noticed as they wander through your house in the early spring. Later in the summer you may see them moving to and from your house as they gather food. You may also notice piles of sawdust, insulation or other materials they dump out of their nest or you might hear the rustling sounds they make inside walls, ceilings or floors.



Carpenter Ant Damaged Wood. Note how they clean the area. Sawdust is deposited out of the area as this is where they live. They do not eat the wood.

Carpenter ants nest inside wood and can seriously damage it as they hollow out areas in which to live. They may also live in and damage foam insulation, particle board and other building materials. The all black carpenter ant can damage sound wood but the red carpenter ant will only damage rotten wood and other soft materials.

Damaged wood is rarely visible although small holes through which sawdust is ejected can sometimes be seen.


Carpenter ants eat a wide variety of things. A large part of their diet is other insects and honeydew from aphids that they find on trees and shrubs. They also will eat dead animals, sweet materials from plants, humming bird nectar and many things they find in kitchens. Carpenter ants do not eat wood.

Conditions Favouring Carpenter Ant Infestation

Things To Do So Carpenter Ants Will Not Like Your House

We have been able to identify several things which favour carpenter ant infestations in homes. One of the most obvious is when a home is built in an area with a lot of natural carpenter ant habitat: areas with a lot of evergreen trees, stumps and logs.

Vines, tree branches, bushes and other vegetation growing on or touching your house will make it very attractive to carpenter ants. So will the presence of water leaks, improperly-stored firewood, and soil touching the siding of your house.

Timetable of Carpenter Ant Activity

  •     January, February March: Worker ants, winged males and winged females may be seen inside. Worker ants are often found in the kitchen.
  •      April: Ants begin to go outside for food. Outdoor nests become active.
  •     May: Winged males and females leave outdoor nests on mating flights
  •     May, June, July, August: Ants are active. Nests are expanded and sawdust ejected. Feeding pathways are evident outdoors.
  •     September, October: Ants normally go dormant but may be seen during late warm summers.
  •     November, December: Ants are inactive and not seen.


Effective Carpenter Ant control is basically a 2 step program and requires a cooperated effort from us, for the safe and effective application of pesticides and other control agents, and from you, for management of environmental conditions on the property which favour the presence of carpenter ants.

1. What We Do

  • Inspect: We look for carpenter ant nests (there may be more than one) by searching for ants, nest debris and the "sawdust" the ants create. We listen for the rustling noises ants make in their nests. We follow ants as they collect food and carry it to their nests. Sometimes we use repellent sprays to "flush" ants out of their hiding places. We search all accessible parts of a building including living areas, attics, basements crawl spaces, walls and roofs. Outdoors, we inspect trees, stumps, logs, landscaping ties and fences.
  • Treat: All carpenter ant nests discovered are destroyed. This may involve drilling small holes into infested wood and injecting appropriate insecticides into the nest. It may involve opening nest areas, vacuuming up the ants and applying appropriate insecticides, or we may even physically remove the infested wood.
  • Barriers: Insecticidal barriers are applied to areas carpenter ants must travel in their search for food. Residual insecticidal sprays are applied to foundations. Dry insecticides are applied into wall voids. Sometimes slippery Teflon(r) barriers are applied to foundations to force ants to travel in treated areas.
  • Follow-up: Follow-up work is essential to good carpenter ant control. Each month following our initial treatment (April through September) we check outdoor areas for signs of ongoing carpenter ant activity. We search foundation areas, fence lines, pathways and overhead wires for ants. High-risk areas may be retreated with barrier insecticides. If ants are found, their trails are treated with appropriate insecticides. Whenever necessary, additional indoor work is scheduled.

2. What You Should Do

  • Correct Moisture Problems: Carpenter ants lay their eggs in damp wood. It is essential that roof leaks, plumbing leaks, inadequate ventilation, wood-soil contacts and all other sources of wood moisture be eliminated.
  • Remove Dead Wood: Carpenter ants frequently start their nests outdoors. Satellite colonies then move indoors from outdoor nests. Landscape ties, stumps, logs and other wood with a high risk of infestation should be removed from your property. Firewood should moved away from buildings and stacked off the ground.
  • Remove Vegetation: Trees, vines and shrubs growing against the building and overhanging the roof create an ideal carpenter ant habitat. Vegetation can also form "bridges" for ants around insecticidal barriers used in their control. Vegetation on or overhanging the building should be removed.
  • Water Carefully: Insecticides applied on foundations are an important part of carpenter ant control. Please do not wash the insecticides away by allowing sprinklers to wet the foundation.
  • Report Sightings: Carpenter ants are not always active during our inspections. It is a great help to us if you keep us informed about where and what you see the ants doing.

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