The Carpenter Ants have returned!

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Now that the hot weather has arrived, Victoria’s carpenter ants are active again.

Inspect and protect!

They are large ants, 6-12 mm long (3/8-1/2 inch); the flying queen ants may be nearly 2 cm long (7/8 inch). For brief periods in the spring and early summer the winged ants swarm into the air on mating flights. The queens are easy to see as they settle, shed their wings and search for decaying wood to begin their nest. Very few of them will find an ideal site, which is usually outdoors. Their presence does not mean that your house is infested. Carpenter ants are actually beneficial predators that feed on small insects, honeydew and dead and decaying material.

Carpenter ants make two types of nests. If the queen finds moist, decaying wood, she tunnels into it to begin the main nest. This site must be permanently moist or the eggs and younger larvae cannot survive. Old nests can contain thousands of ants, but it takes several years for a new nest to build up to a few hundred individuals. Main nests are usually outdoors in rotting stumps, trees or in decaying landscape timbers. They can become established in houses where wood in the structure has begun to decay. Although carpenter ants do not eat wood, they do tunnel into it to make their galleries. Once they establish a nest in damp wood they will eventually damage the structure by tunnelling from the decaying wood into the sound wood. Carpenter ants also make satellite nests where they care for the older larvae and pupae that tolerate drier conditions. These nests are often in wall voids and eaves, ceilings or under insulation in attics or crawl spaces. Most nests in houses are satellite nests that maintain communication with the main nest.


The best protection is to maintain dry conditions with proper construction and maintenance, remember that anywhere wood is in contact with soil there is a risk of carpenter ant infestation.

  • Repair wood damaged by moisture, ventilate damp areas, clean gutters to avoid clogging, which leads to water damage to siding or roof.
  • Store firewood on raised platforms, well away from the house.
  • Prune trees so branches don’t touch the house.
  • Remove all nearby rotted stumps or logs. Check for rotting landscaping wood.
  • Ensure that wood of the siding or structure isn’t in contact with soil at any point around the house foundation.


The key to control is finding the main nest, where the queen is laying eggs. This requires thorough inspections and an effort to follow foraging ants back to their nest. If you see ants inside your house in an evening, it is worth hiring  professional to investigate for a nest inside your  house. While you can inspect and treat on your own, some chemicals can be harmful and my experience is that if the queen sees the effects of your treatment, she may relocate her nest. You see dead ants and think you killed them all….without realizing the rest have relocated

Carpenter ants use the same trails over and over and are most active at night.

Professionals will look for signs of nesting activity, such as mounds of loose shavings or sawdust beneath a crack in a wall or eave space. Sometimes you can hear rustling sounds in the walls (use an inverted glass or rolled up paper tube to amplify the noise).

Choose a service that will conduct a thorough inspection for the main nests and that is willing to discuss with you, in detail, the various treatments. To prevent the problem from recurring after treatment, replace or repair any damaged timbers and correct moisture problems.

If your treatment professionals offer a warranty it may make sense to have them back again for an inspection before the warranty expires

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