Mosquito Control

 

 

Mosquito populations in Calgary can increase quickly after heavy rain, especially when warm weather follows. Most mosquitoes found around homes are not coming from the Bow River or another large body of water. They are often developing in small amounts of standing water found on residential and commercial properties.

The most effective way to control mosquitoes is to remove their breeding sites and kill the larvae before they become flying adults.

How to Prevent Mosquitoes Around Your Calgary Property

Mosquitoes need standing water to reproduce. Depending on the temperature and mosquito species, larvae can sometimes develop into adults in approximately one week. Water does not need to be deep, clean, or permanent. A shallow container that fills after a Calgary thunderstorm can be enough.

Check your property after rain and look for anything that is holding water.

• Plant saucers
• Nursery pots and unused planters
• Buckets and watering cans
• Wheelbarrows
• Children's toys
• Garbage can lids
• Recycling bins
• Tarps and patio furniture covers
• Old tires
• Clogged gutters
• Window wells
• Bird baths
• Rain barrels
• Decorative ponds and fountains
• Low areas of the yard that remain wet after rain

If the water can be removed, dump it out. Turn empty containers upside down or store them under cover so they do not refill during the next storm.

Simply pouring out the water may not remove every mosquito egg. Some mosquito species lay eggs on the inside walls of containers, just above the waterline. These eggs can remain in place and hatch when the container fills again. Scrub the inside of buckets, bird baths, plant saucers, and similar containers before refilling or storing them.

Empty Water Regularly

Bird baths, pet water dishes, and other small outdoor water containers should be emptied, cleaned, and refilled every few days during mosquito season.

Do not just add fresh water to the existing water. Dump the old water out completely and rinse the container before refilling it.

Calgary can go through long dry periods followed by sudden heavy rain. A container that was dry all month can become a mosquito breeding site overnight, so it is a good idea to inspect the yard after every major rainfall.

Maintain Rain Barrels

Rain barrels are one of the most common mosquito breeding sites around homes.

Use a tight-fitting lid and cover all openings with fine insect screen. Check the screen regularly for gaps, tears, or places where mosquitoes could enter around the downspout.

Overflow outlets should also be screened. A screened lid will not help if mosquitoes can enter through an uncovered overflow pipe.

If mosquito larvae are already present, or if the barrel cannot be fully sealed, use Mosquito Dunks according to the package directions.

Clean Gutters and Drainage Areas

Clogged gutters can hold shallow water for days after a storm. Remove leaves, soil, and plant debris so water can drain properly.

Check downspout extensions, catch basins, drainage trays, and low areas beside the foundation. Correct any drainage problem that allows water to remain for more than a few days.

Window wells should have proper drainage and covers where appropriate. Leaves and debris can block the drain and create a sheltered pool of water that is easy to overlook.

Manage Plant Saucers and Outdoor Nursery Pots

Plant saucers are especially easy to miss because they are hidden under foliage. Empty them after watering or rainfall.

If a plant must sit in a saucer, avoid leaving water in the saucer for extended periods. Elevating the pot slightly can also help the saucer dry more quickly.

Stack unused nursery pots upside down or store them inside. A stack of upright pots can collect water in several different places.

Keep Ponds and Water Features Moving

Mosquitoes prefer still or slow-moving water. Pumps, fountains, waterfalls, and aeration can make a water feature less suitable for mosquito larvae.

Remove decaying leaves, algae, and other organic debris that provide food and shelter for larvae.

Water movement does not guarantee complete control. Mosquitoes may still reproduce in sheltered corners, clogged filters, inactive fountains, or areas where the water is not circulating properly.

For standing water that cannot be emptied or kept moving, use Mosquito Dunks according to the label.

Reduce Mosquito Resting Areas

Adult mosquitoes often rest during the day in cool, shaded, humid areas.

Keep grass trimmed and thin out extremely dense vegetation near decks, doors, walkways, and seating areas. Remove weeds and unnecessary plant growth from under stairs, behind sheds, and around outdoor storage.

You do not need to remove all of your plants. The goal is to improve airflow and reduce dark, damp areas where mosquitoes can remain protected during the day.

Use Outdoor Fans

Mosquitoes are weak fliers. A fan directed across a deck, patio, greenhouse work area, or outdoor seating area can make it much harder for them to land.

Fans do not reduce the population, but they can provide immediate relief while breeding sites are being corrected.

Repair Screens and Seal Entry Points

Inspect window screens, screen doors, and basement window covers for holes or loose edges.

Make sure doors close properly and replace damaged weather stripping. Avoid leaving unscreened doors open during the evening, especially after rain when mosquito activity may be higher.

Killing Mosquito Larvae

Mosquito Dunks

Mosquito Dunks contain Bacillus thuringiensis israelensis, commonly known as BTI.

BTI targets mosquito larvae while they are feeding in water. The larvae consume the bacteria, stop feeding, and die before they can develop into adult mosquitoes.

Mosquito Dunks are useful for standing water that cannot easily be emptied, including:

• Rain barrels
• Decorative ponds
• Unused fountains
• Water gardens
• Livestock water troughs
• Drainage areas that remain wet
• Other suitable standing-water sites listed on the product label

Mosquito Dunks kill the larval stage. They do not kill adult mosquitoes that are already flying around the property.

Always follow the package directions. The required amount depends on the size of the water source.

Killing Adult Mosquitoes Indoors

Wilson Fly Out House Insect Killer

Wilson Fly Out House Insect Killer is intended for indoor flying insects and lists mosquitoes among the target pests.

It provides fast knockdown when adult mosquitoes enter a home, office, garage, or other indoor area. It is useful for immediate control, but it will not stop more mosquitoes from appearing if there is still a nearby breeding site.

For the best results, use it together with standing-water removal and larval control.

Doktor Doom Commercial Long-Lasting Surface Residual Insect Killer

Doktor Doom Commercial Long-Lasting Surface Residual Insect Killer is labelled to kill mosquitoes that land on treated surfaces.

This product leaves an insecticidal residue and is intended for approved structural surfaces and locations listed on the label.

It should not be sprayed directly on plants. Remove or protect pets, aquariums, and exposed food before treatment, and follow all ventilation and re-entry instructions on the container.

Other IncrediGrow Products That May Kill a Mosquito on Contact

Several products sold for garden and indoor plant pests contain pyrethrins, pyrethroids, soaps, or oils that may kill an adult mosquito if it is directly contacted by the spray.

These products are primarily sold for the pests listed on their Canadian labels. Do not apply them specifically for mosquito control unless mosquitoes are included on the current label.

• Doktor Doom Go Green Plant Spray
• Doktor Doom Indoor Plant Spray
• Doktor Doom Go Green Total Release Fogger
• Doktor Doom House & Garden Insecticide Spray
• Safer's Trounce Ready-to-Use
• Safer's Trounce Concentrate
• Ortho Bug B Gon ECO Insecticide Concentrate
• Ortho Bug B Gon ECO Insecticide Ready-to-Use
• Safer's Defender Ready-to-Use

These products should not be presented as substitutes for Mosquito Dunks. Killing one adult mosquito does not prevent larvae in standing water from producing more adults.

Products That Should Not Be Used as Mosquito Control

Some pest control products may sound similar or may occasionally affect an individual mosquito, but they are not practical mosquito-control products.

• BTK products: BTK is intended for caterpillar larvae. It is not the same strain of bacteria used in Mosquito Dunks.
• Beneficial nematodes: Nematodes sold for fungus gnats and soil pests are not intended for mosquito larvae in standing water.
• Predatory mites: Predatory mites live on plants or in growing media and do not control aquatic mosquito larvae.
• Ladybugs: Some lady beetle species have been documented eating exposed mosquito eggs, but ladybugs are not a reliable mosquito-control method.
• Yellow sticky traps: They may accidentally catch an occasional mosquito but are not especially attractive to mosquitoes.
• Insecticidal soap alone: Soap must directly contact a susceptible insect and does not provide practical control of a mosquito population.

What to Do After Heavy Rain in Calgary

After a major Calgary rainstorm, inspect the property within the next day or two.

1. Empty buckets, saucers, toys, tarps, and other containers.
2. Scrub containers that have visible residue or a waterline.
3. Check gutters, window wells, and drainage areas.
4. Confirm that rain-barrel screens and lids are secure.
5. Restart pumps or fountains that have stopped circulating.
6. Treat standing water that cannot be removed with Mosquito Dunks.
7. Trim excessively dense vegetation around patios and entrances.
8. Repair damaged window and door screens.

Repeat the inspection regularly through the summer, especially after thunderstorms and periods of irrigation.

Our Recommendation

Start by removing standing water. This is the most important step and costs nothing.

Use Mosquito Dunks in suitable water sources that cannot be drained. This kills mosquito larvae before they become biting adults.

If mosquitoes are already inside, use Wilson Fly Out House Insect Killer according to the label for immediate knockdown.

Use Doktor Doom Commercial Long-Lasting Surface Residual Insect Killer only on approved surfaces and in the locations permitted by the label.

Adult sprays may provide temporary relief, but breeding-site removal and larval control will have a much larger effect on the number of mosquitoes around your Calgary property.