Ausable Bayfield Conservation Authority

Reducing mosquito habitat

Strategies to keep mosquito numbers down

Reducing mosquito habitat and preventing mosquito bites

If you are interested in helping to reduce mosquito habitat there are ways you can help on your property.

The following is information from the Ontario Ministry of the Environment and Climate Change. (It may be subject to change - please consult the original source for most accurate information).

  • Remove stagnant water breeding areas
  • Take personal precautions to avoid being bitten by mosquitoes

These are among the first lines of defence against West Nile virus.

Residents are strongly encouraged to remove breeding sites and practise personal protection against mosquitoes.

Specific practical advice includes:

  • Clean up and empty containers of stagnant water, such as old tires, flower pots, wheelbarrows, barrels or tin cans that are outdoors. Drill holes in the bottoms of used containers so water can't collect. Change water in bird baths weekly.
  • Don't let things pile up. Clear leaves and twigs from eaves troughs, storm and roof gutters throughout the summer. Make sure drainage ditches are not clogged. Check flat roofs frequently for stagnant water.
  • Collect lawn cuttings, raked leaves or other decaying debris, such as apples or berries that fall from trees, and recycle or mulch so that organic matter does not end up in storm sewers as a food source for mosquito larvae. Turn over compost frequently.
  • Fill in low depressions in lawn areas. Clear out dense shrubbery where mosquitoes like to rest.
  • Immediately remove water that collects on pool covers. Make sure the pool's pump is circulating. Turn over wading pools when not in use.

  • Check window screens for holes and make sure they fit snugly into the window frame so mosquitoes will not get indoors. If you don't have screens, consider keeping windows closed between the hours of dusk and dawn.
  • Make sure you wear light-coloured clothing such as long-sleeved shirts or jackets and long pants.
  • Tuck pants into socks for extra protection when going outside between the hours of dusk and dawn.
  • Use insect repellent that has been approved for use in Canada (It will have a PCP number on the front label) and follow directions for use carefully.

Here is some information from Environment and Climate Change Canada (visit their website for most up-to-date information):

  • Stagnant water located in bird baths should be changed at least once a week.
  • Yard waste, such as lawn cuttings and raked leaves, which are present in gutters or storm drains prevent water from flowing and harbour perfect breeding conditions for mosquitoes.
  • Low-lying depressions in lawn areas where water can collect should be filled in.
  • Leaves and twigs can block roof gutters and eavestroughs and prevent proper water drainage.
  • Compost should be turned over frequently and areas of organic matter, which provide a food source for mosquito larvae, should be collected and recycled immediately.
  • Stagnant water of any kind is another breeding area for mosquitoes.
  • Open or broken window screens and attic vents offer perfect avenues for mosquitoes to make their way into your home. Window screens should fit snugly into the frame, vents should remain closed and for further prevention, windows should also be shut during the hours of dusk and dawn.
  • Pool covers often collect water and should be emptied right away.
  • Wading pools need to also be turned over when they are not in use.
  • Toys and other objects around the yard should be placed in an area where they won't collect rainwater.
  • Mosquitoes are often attracted to containers of standing water in wheelbarrows or tires that are left outside. To avoid this, drill holes in the bottom of containers to allow water to flow out or turn over those items that are not in use.
  • Leaky faucets should be closed tightly as water build-up can create breeding grounds for mosquitoes.

It's important to clean up around your house because most mosquitoes may fly in a radius of about one to three kilometres from their breeding site.

Here is some information from Health Canada:

  • Control breeding sites.
  • Mosquitoes breed in stagnant water. Remove any possible breeding sites where mosquitoes could lay eggs, even in very small quantities.
  • Eliminate sources of standing water in your yard. Store flower pots, watering cans, boats and wheelbarrows upside down.
  • Empty tire swings of any water and, if possible, replace them with another type of swing.
  • Cover any garbage, recycling or composting containers, to prevent water from accumulating in them.
  • Drill holes in the bottom of containers that must be left outdoors uncovered.
  • Replace water in bird baths and outdoor pet dishes at least twice a week to help eliminate stagnant water.
  • Empty your rain barrel if the water is more than a week old, unless it is properly protected with a fine-screened cover.
  • Keep your swimming pool aerated, cleaned and chlorinated, even if it is not being used.
  • Dump any water that collects on your swimming pool cover.
  • Turn over plastic wading pools when they're not being used. Change the water in your wading pool at least twice a week.
  • Keep your gutters clean.
  • Check under shrubbery and lawn coverings for hidden containers or pooling water in low spots.
  • Modify the landscape to eliminate water that collects in low areas on your property. Mosquitoes can develop in any puddle that lasts more than 7 to 10 days during warm weather.
  • Repair any leaks from outdoor water pipes, joints or hoses. Replace washers on outdoor taps that drip.
Using Pesticides to Control Mosquitoes Around the Home

Homeowners can hire a licensed pest management company to properly and safely apply pesticides to control mosquitoes on their property. These companies are listed under Pest Control in the Yellow Pages of the telephone book. In Ontario, a commercial pest management company must have an Operator's licence issued by the Ministry of the Environment to employ licensed applicators to apply larvicides - pesticides used to control mosquito larvae, or adulticides - pesticides used to control adult flying mosquitoes.

  • Homeowners can use domestic pesticides on their own property to control mosquitoes. However, the Ontario Ministry of the Environment strongly recommends that homeowners focus efforts on personal protection and removing mosquito breeding sites to reduce the chances of being bitten by mosquitoes.

  • Applying Larvicides

  • Two domestic larvicide products are available containing Bti (Bacillus thuringiensis israelensis) and methoprene - consult your local hardware or garden centre for product availability- for use by homeowners without the need of a licence or permit if used on their own property. This product can be applied only to water that is wholly contained on the property and has no outflow off of the property. This includes water in rain gutters, discarded tires, ornamental ponds, puddles, rain barrels, flood water pools, and roadside ditches if the property owner is responsible for the ditch and the ditch has no flowing water. Do not apply to storm water drains. A larvicide can only be applied into a catch basin by a licensed exterminator who also has obtained a permit from the Ministry of the Environment and permission from the municipality.

    Private property owners (houses, condominiums and apartments, parking lots, shopping malls, schools, commercial and industrial properties, etc.) who have catch basins located on their property that flow to municipal storm sewers cannot apply larvicides into these water bodies. A larvicide can only be applied into a catch basin by a licensed exterminator who also has obtained a permit from the Ministry of the Environment and permission from the municipality. Screening can be placed over a single back yard catch basin and secured with stones to prevent mosquito adult access. Ensure the screening is frequently cleaned of debris so as not to hamper water drainage into the catch basin.

    There are domestic Bti larvicide products available to land owners that can be purchased and used without need of a licence or permit if the stagnant water body is wholly contained on the property with no outflow off of the property. This naturally occurring bacterium provides effective control at certain stages of a mosquito's life cycle. Larvae must be present in order for the Bti to be effective. Since the product lasts only a day or two and mosquitoes can complete their life cycle within seven to ten days, repeated applications of this larvicide are necessary to achieve effective mosquito control.

    Artificial ponds can be stocked with fish (e.g., gold fish and Koi) that eat mosquito larvae (do not stock ponds that have an outflow to natural water sources if stocking with non-native fish). Consult the Ministry of Natural Resources (MNR) before stocking any water body. Consider using an aerator to create water surface movement. The local MNR office must be contacted if a landowner is considering draining a wetland and/or a pond. Applying Adulticides

    Private property owners may use adulticides labeled for domestic use from a ready-to-use aerosol or a fogger on their own property without a licence. Several adulticide products containing pyrethroids, malathion and propoxur are available in garden centres and hardware outlets for domestic use. Users are cautioned to apply these products according to label directions to ensure the application is to target areas such as trees and bushes and to ensure that neighbours are not affected. Users should be aware that backyard treatments may be effective only for a short period of time, due to the ability of mosquitoes to fly the short distances from other properties. More information

    Additional fact sheets on the use of pesticides in preventing the spread of West Nile Virus are available on the ministry's Web site at:

    Information on West Nile Virus is available on the Ministry of Health and Long-Term Care's Web site at or by calling the toll-free MOHLTC West Nile Virus INFOline at 1-877-234-4343.

    Fact sheets on pesticides for mosquito control are available on Health Canada's Web site at

Search keywords: mosquito, mosquitoes, mosquitos

Do wetlands encourage mosquitoes?

Healthy, functioning wetlands can actually reduce mosquito populations. Some areas that are drained could still hold enough water after a rain to breed mosquitoes and drained areas could actually produce more mosquitoes. That's why it's important to find effective ways to design and manage areas to limit mosquito growth - in some cases that may mean eliminating standing water in low areas where water pools, and in other cases it may mean increasing flow or even increasing the depths of water in some locations. Building an effective ecosystem in a wetland design can encourage natural predators that eat mosquitoes.

Here is a fact sheet from a U.S. source, the State of Indiana: 

Joint response to keep mosquito numbers down in Parkhill

Ausable Bayfield Conservation Authority (ABCA) continues to work in partnership with the Municipality of North Middlesex and the Middlesex-London Health Unit, and the contracted firm undertaking the municipality's mosquito abatement program, to develop short-term and long-term strategies to reduce the number of mosquitoes in Parkhill now and in the future to avoid a repeat situation of the high number of mosquitoes which were in the community in 2011.

Numbers of mosquitoes were lower in 2012 and 2013. The health unit continues to monitor mosquitoes for numbers and type (for example, looking to see if there are any vector mosquitoes capable of carrying West Nile Virus).

The main area of focus for mosquito habitat removal is a 25-hectare (62-acre) management area downstream of Parkhill Dam. The public has also identified other areas around the dam and within town where mosquitoes could also breed.

ABCA staff members with expertise in environmental management have already increased efforts to reduce mosquito habitat and have undertaken in-depth field investigations in the area where mosquitoes are heavy to recommend the most effective ways to reduce their numbers. 

The conservation authority has worked closely with the municipality on projects to remove obstructions such as logjams and maintain flow in watercourses to prevent mosquito breeding. The conservation authority has also done maintenance projects to prevent water from ponding and to reduce mosquito habitat.

The municipality continues to do a larvicide program to keep numbers down.

The Municipality of North Middlesex invited a committee of interested citizens to assist in the control of mosquitoes in Parkhill after the 2011 year when mosquito numbers were very high. One of the actions the municipality took to prevent a repeat of the high mosquito numbers was the formation of a special committee of council which involved citizens of the community to meet and strategize on an approach for the long-term control of the mosquito population. These recommendations were then forwarded to council for consideration.  The municipality has since conducted a clean-up of the Cameron-Gilles Drain which runs through the centre of Parkhill.  There has also been clean-out of garbage and brush along the drain and loading onto municipal vehicles for removal under municipal supervision. A sign-up list is available at the Town Hall or you can call and leave your name and daytime phone number with reception at 519-294-6244.

Watch for more information at the municipal website at

Click on 'mosquito information.'

Although mosquito numbers have declined since the high numbers of 2011, the Municipality of North Middlesex, the Middlesex-London Health Unit, and the Ausable Bayfield Conservation Authority (ABCA) continue to work in partnership to keep mosquito habitat down in the area by reducing ponding, maintenance, projects to remove obstructions and maintain water flow to prevent stagnation and mosquito habitat, and monitoring.

For more information download one or more of these fact sheets:


© 2018  | Website by Websmart Inc