Ants are tiny insects and may be black, brown, red, or yellow. Adult ants range in size from as small as 1 millimetre (1/16 to 1/32 inch), like little black ants and thief ants, to as large as 13 millimetres (1/2 inch), like carpenter ants.
Most ants commonly found in Canada are not aggressive, although some can sting. Ants should be tolerated as much as possible since they cause little damage in the garden. They can even be considered beneficial because they eat other insects like young silverfish and moths.
Species known to invade homes in Canada include the carpenter ant, the little black ant, the odorous house ant, the thief ant, and the pharaoh ant. Pavement ants can become a nuisance in lawns, gardens, and pathways, as well as indoors.
Carpenter ants are larger than other species, although the sizes of the workers vary. They can cause structural damage to homes as they destroy wood to make room for their nests. Piles of sawdust may mean you have carpenter ants.
How can I get rid of ants?
Ant colonies send out scouts to search for food. Ants are attracted to many types of food. They enjoy eating sugary and greasy foods (like peanut butter or crumbs) and are also attracted to the "honeydew" produced by aphids on infested houseplants. A successful scout leaves a scented trail for other workers to follow back to the food source.
Removing access to food and water is the easiest way to avoid pest problems:
- Store ant-attractive foods in glass jars with rubber gaskets, or in plastic containers with lids that snap tight.
- Keep kitchen countertops clean. Sweep or vacuum the floor often, especially around pet dishes.
- Rinse containers before putting them in the garbage or in recycling bins.
- Empty kitchen garbage containers often.
- Place composters at a reasonable distance from your house.
- Place pet food dishes in a shallow dish of water. Ants can't swim, so they won't be able to get at your pet's food.
- Repair and seal as many visible cracks in the foundation and exterior walls of your house as possible.
- Indoors, caulk along baseboards, cracks, and crevices to keep ants from passing through your house. If needed, use duct tape or petroleum jelly to temporarily seal cracks.
- Ants will not cross sticky barriers. Try placing two-sided tape around the legs of plant stands.
- Flood ant nests repeatedly with a garden hose to encourage the ants to move farther away from your house.
- Pour boiling water and detergent down the nest to temporarily reduce the population of a colony.
- Diatomaceous earth can be placed in cracks and crevices as a non-chemical means of control. This powder is made up of crushed microscopic marine fossils that scratch the outer "skin" of ants, causing them to dehydrate and die. Diatomaceous earth will remain active as long as it is kept dry. It is non-toxic to humans and pets, but be careful not to inhale the dust when applying this product.
- Natural gum resins can be applied around the base of trees and vines.
If you use a pesticide to control your pest problem, read the label to make sure you are choosing the right product for the right pest. Follow all label directions and warnings carefully. Always look for a Pest Control Products (PCP) number on the label so you know the product has been approved by Health Canada. See Use pesticides safely for more information on using pesticides safely.
Many chemical products can be used by consumers to control ants:
- Chemicals, sprays, and dusts can be used effectively as barrier and nest treatments. Applying a chemical directly on the nest may eliminate colonies. Anthills show where the colony has built a nest, so look for anthills in your yard or follow the ant trails back to the nest. Nests located indoors in wall voids can be treated with dusts that can be puffed into the area.
- Chemical barrier treatments can be applied to baseboards or door and window frames to keep outdoor nesting species from searching for food indoors. Spraying indoors where trails have been noticed may cut off food and water sources for an indoor nest and encourage the colony to split into multiple new colonies. If the treatment seems to increase the number of ants, try using a bait system to control them.
Ants gather food and bring it back to the nest to feed ant colony members. So a bait system must work slowly enough to allow the poison to be fed to all members of the nest. This is a highly effective way of getting rid of nests. Baits containing boric acid are generally of low toxicity to other animals.
- Place bait stations directly in the path of foraging ants, but out of the reach of children and pets. Ant trails are commonly found along baseboards, the carpet edge along walls, or along the edges and inside corners of cabinets.
- Use plenty of bait stations. Two different baits at the same time will give better results.
- Keep baits available for at least two weeks. Repeated bait applications may be needed.
- Do not use chemical sprays to kill ants while using a bait system, or the bait system will not work. Reapply the bait if needed.