There are about seventy species of ants in Alberta. The most common groups are field ants and carpenter ants. Both can be thought of as either a beneficial insect or a pest depending upon their location.

Field Ants

In lawns, their mounds are typically only two to three inches high and composed of small soil grains removed from the excavated galleries below.

Ants are opportunistic feeders - sometimes predaceous but usually scavengers and/or aphid farmers. When the population at any one nest becomes excessive, queen ants will be produced to start other nests. Ants from non-related nests will fight to protect local territory, often raiding nests to bring back pupae to their nests.


Control of field ants is often difficult as the removal of one nest seems to allow other colonies nearby to expand into this new territory. A few techniques can be used to control ants in these locations:

  1. Pour large quantities of boiling water slowly into the nest being careful not to allow too much surface run-off. Expect some turf damage.
  2. Apply diatomaceous earth around the entry hole to the nest. The workers will carry it down into the nest and some control will result. Diatomaceous earth is available at garden centres.
  3. Apply a chemical ant killer to the nest per product label requirements. A selection of products is available at garden centres.
  4. Flood the nest site daily until they leave to find a new site. This method may just move the nest somewhere else in your yard.

Things to remember about controlling field ants in your yard:

  • Ants will not establish a nest where there is frequent irrigation, so many nest sites in a lawn can be an indication of drought stress. Find the common food gathering trails the ants are using and set ant bait traps along these.
  • Keeping your lawn at least 10cm long will discourage ants from beginning their nests. Ants prefer hot, droughty sites with short grass.
  • Always look for more than one nest.
  • Coexist with them if at all possible as they serve a purpose in nature as scavengers and predators.
  • Try the least hazardous solutions first.
  • If choosing a chemical application, follow label requirements.

Carpenter Ants

The Black Carpenter Ant (Camponotus pennsylvanicus) is common in Canada east of the Rockies. These ants speed the decomposition of deadwood in the forest, which benefits the ecosystem by recycling organic materials. However, they become a pest when they start nests in and around our homes and buildings.

Carpenter ants can pose a serious threat to a building's structural integrity and should be dealt with promptly when found inside buildings.

While these ants live inside of wood, their food sources are the same as most other ants: honeydew from aphids, live and dead insects, food residues and plant sap from weeping wounds.


Control of carpenter ants is usually easy once the nest has been found. Control should include these three steps:

  1. Find and eradicate all nests using domestic class chemical products and/or removal of infested timbers.
  2. Ensure that all rotting wood in your yard or nearby has been removed and disposed of offsite.
  3. Ensure that all wood surfaces in contact with the soil are treated with wood preservative.

Things to remember about controlling carpenter ants in your yard:

  • Always look for more than one nest. If any nests are inside the house call a professional exterminator.
  • Coexisting with them is a bad idea for residential or commercial properties, as their activities can cause serious structural damage.
  • Try the most effective solution first.
  • If choosing a chemical application, follow label requirements.


Mound of Ants
Ants on leaves
Close up of an ant on tree leaf
Ant dragging a caterpillar