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Insects and other arthropods

Prevent and control ant intrusion

Camponotus sp, Québec, Canada.
Photo: Insectarium de Montréal (René Limoges)
Camponotus sp, Québec, Canada.

Like many other “nuisance” species, ants need water, food and shelter for their nest. By blocking their access to these essential elements, you can keep them from getting into your house. If they are already in your home, the methods below can help you get rid of them.


Here are some tips to prevent ant infestations in your home:

  • Keep food in hermetically sealed containers. Tiny pharaoh ants can get into containers that are not properly sealed.
  • Check bags of pet food.
  • Manage waste carefully. Do not leave anything edible (leftovers, food waste, bread crumbs) on countertops and floors or in the sink. Keep all surfaces clean. Sweep or vacuum regularly – every day if possible.
  • Create a barrier around pet food bowls by placing them in a dish filled with soapy water (if there is no soap in the water, ants can float in the water to reach their target).
  • Rinse all food containers before throwing them away. Place organic waste in a sealed container or put it outside in a composter. Be sure the composter is not right next to the house.
  • Install sticky barriers to keep ants from climbing. Double-sided tape works well for this purpose. Place it around table legs or plant stands.
  • Find the places where ants are entering your home and seal them off with silicone-based caulking, which cracks less easily than plaster. Seal off the edges of baseboards and around windowsills as well as any cracks you see.
  • Inspect, clean and repair gutters. Place screens in any openings, including vent openings.
  • Use a cleaning product to remove ants’ chemical trails (unless you are using boric acid-based bait).
  • Prune tree and shrub branches so that they do not touch the house (ants will jump off branches to explore new territory). Prune damaged trees; remove tree stumps.

To prevent carpenter ants from building a colony in your home:

  • Eliminate sources of humidity that could affect wood. Repair leaky pipes and roofs, and make sure humid areas in your house are well ventilated.
  • Eliminate any rotting wood around your house. Don’t store large pieces of wood near the foundation.
  • Store heating wood by elevating piles of logs above ground levek. Cord wood away from buildings. Before bringing wood into the house, knock logs together so that any insects on them will drop to the ground. Once you have brought in the wood, inspect it regularly and eliminate any ants found indoors.

Direct control

  • Time is needed to eradicate ant colonies inside a dwelling. One of the best solutions is to use bait with slow-acting toxic agents, such as boric acid (or borax). You can create your own bait.
  • In the event of major infestations, it can be difficult to eliminate ant colonies, and it is recommended that you consult professional exterminators. If the infestation involves carpenter ants, it may take as long as two years to eliminate the entire colony.
  • If you opt for chemical insecticide, get advice from a specialist in order to choose the product that is the least toxic and best adapted to your situation. Follow the manufacturer’s instructions carefully, proceed with caution and remember that most chemical insecticides are harmful to you and to the environment.

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