Carpenter Ants

Carpenter ants are one of the most impressive species of insect pest we have native to the coastal temperate rainforest.  Unfortuanately they can also be very damaging to our homes, and they can cause a lot of stress and grief to homeowners confronted with the site of piles of sawdust being pushed out of their ceiling, or hundreds of swarming ants flying out of their walls!

Carpenter ants get their name from the fact that they excavate their nests in wood, creating smooth tunnels and galleries in the wood. They are one of the most structurally important pests here in the Metro Vancouver and Fraser Valley area. While they do not eat wood (like termites do), they can definitely damage it, leading to potential structural damage to your home or business. As the ants excavate their nests, they remove and kick out "frass", further weakening wood which often already has some moisture damage.

How can you tell if you have carpenter ants?

  • Sawdust or "frass" piles being kicked out of a wall or ceiling - this is from the ants excavating living space out of the wood in your home.
  • Winged reproductive ants flying inside your home in the springtime.
  • Worker ants foraging for food inside your home in the springtime.
  • Crinkly scratchy noises in the walls or ceiling - this is the sound of an active nest, and it can be heard quite distinctly, especially at night or during the day when the room is quiet.

Carpenter ants feed on a wide variety of foods containing either protein or carbohydrates. Examples include honey, sugar, meat, grease, and their absolute favourite, the honeydew produced by aphids.  Carpenter ants are also major predators of other insect species. Of the entire colony, which may have thousands of individuals, only 5 to 10% will be out looking for food at any one time.  So if you see a huge trail of big black carpenter ants, remember that you are only seeing a small number of the ants in that colony!

While there are 10 species of carpenter ants native to BC the two most common structure infesting species are Camponotus modoc and Camponotus vicinus.  All carpenter ant species are polymorphic, which just means they have multiple sizes of worker - 3 in this case.  What this means is that they are not just "big black ants" - they may in fact be small (minor workers) or medium sized ants, and there are a variety of colour patterns amoung the various local species.

C. modoc are typically described as "big black ants" - they are the largest ant found locally (ranging in size from 6 to 17mm in length) and are all shiny black (with red legs, if you look closely).  The winged female reproductives (they are even bigger than the biggest workers) which swarm out of nests from late March into May are the source of many a frantic phone call from homeowners. C. Modoc is  the most common carpenter ant species throughout Vancouver and the Coast and if you live in a moist area or a heavily treed area, or both, you are likely to see this ant.

The main or parent nest is located in moist wood, including trees, stumps, landscape ties or water damaged wood in a structure. The single queen ant eggs will be in this parent colony. Mature carpenter ant colonies typically have satellite nests located within structures in wood studs (including in dry sound wood), siding and joists, wall voids, and insulation (both fiberglass and foam core). Satellite nests are established as the main colony begins to require more territory or resources. These nests may be located as far as 750m from the parent nest. Colonies of C. modoc can contain up to 50,000 ants and can thrive for over two decades.

C. vinicinus are also large ants but they are red and black. These ants are similar in biology and habits to C. modoc but this species can have colonies of more than 100,000 workers due to the presence of multiple egg laying queens. C. vicinus is also prevelant in damaged wood but will nest in areas that are dryer than the other common carpenter ant, C. modoc.

New carpenter ant colonies are established after a mating flight (or swarm) of winged reproductives. These swarms are seen in spring time and can be alarming as large winged ants emerge from your home. If you see a swarm of carpenter ants in your home, there are likely nest sites inside your home.  If you see swarmers outside, there will be an established colony nearby.

Successfull carpenter ant control involves finding and removing or treating the nests in your structure, and preventing re-infestation from the remaining ants in the colony which continue to exist in the neighbourhood around you.

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