The no-harm approach to managing mosquitoes
By Angie Caunce-Paull, Environment Committee
There is no way to sugar-coat it. Mosquitoes suck.
How are we supposed to enjoy our outdoor spaces when we are getting eaten alive by relentless vampire insects? When pest control companies come along offering to rid your backyard of mosquitoes, it’s very tempting to give them all your money in exchange for some sweet relief. But that relief comes at a very high price.
What “spraying for mosquitoes” actually does
Mosquito sprays and foggers use synthetic chemicals called pyrethroids to kill all mosquitoes in a specific area. These chemicals mimic naturally found toxins called pyrethrins that are derived from chrysanthemum flowers. Both are broad-spectrum insecticides that are highly toxic to a wide variety of insects including bees, butterflies, ladybugs, beetles, and dragonflies, killing on contact. The spray does not discriminate. It’s a chemical blow torch.
Pyrethrins target the nervous system, resulting in paralysis, loss of motor control, and ultimately death. Inspects don’t need to ingest the poison, they absorb it through their exoskeleton. And because insects are so small, even a tiny dose can be lethal.
When it rains, the toxins run off into the storm drains and straight into the Ottawa River with devastating results to aquatic life.
The bracing truth about mosquito coils
If you thought (like I did just a month ago) that burning mosquito coils keeps pests away because they “don’t like the smoke”, I have bad news. The coils use the exact same chemicals in smoke form. Any insect that flies through the smoke (that is now airborne and drifting around), even at a tiny dose, will die. That includes every bee, every caterpillar, every firefly. In fact, the smoke carries the airborne insecticide, which lingers in the air and then settles on plants. Those plants are now deadly to any insect that interacts with them. When it rains, the poison particles are rinsed off of plants, lawn furniture, and decks and are carried into the soil. In the soil, the toxin kills beneficial microbes and fungi that are vital for healthy soil and carbon capture.
It gets worse. Birds feeding nestlings depend on high volumes of caterpillars and soft-bodied insects. Pyrethroid-treated lawns have been shown to lead to chick starvation in species like chickadees and warblers. And birds and mammals exposed to sublethal doses have shown signs of neurotoxicity: confusion, convulsions, disrupted flight.
Insects are good for your yard – even your lawn!
Even if you don’t care much about insects, it’s worth knowing that beneficial insects quietly support the health of your yard in ways you can actually see. Bees, butterflies, and beetles help pollinate plants and keep flowers blooming. Predators like dragonflies, lacewings and ladybugs keep pests like mosquitoes and aphids in check without chemicals. And deep in your soil, countless tiny creatures break down organic matter, keeping your lawn spongy, green, and able to handle rain without flooding or erosion. When we spray to kill all insects, we don’t just lose the bad ones — we wipe out the good ones too. That means more mosquitoes, not fewer, and lawns that need more effort and chemicals to maintain. Even in a small yard, protecting beneficial insects can lead to less spraying, healthier grass, and a safer space for your family to enjoy.
Fear not! I have two solid mosquito control recommendations for you. And no, neither of them involve citronella candles.
How mosquitoes reproduce
Female mosquitoes lay 100-300 eggs at a time in standing water. The eggs hatch into larvae in about 24-48 hours. The larvae are tiny, wiggling creatures you can see at the water’s surface. They breathe air through a little snorkel and eat algae and microbes. Note: the snorkel only works in still water, so adding a bubbler to your water features or bird baths can suffocate them.
After 5 to 7 days, the larvae turn into pupae that look like little comma-shaped creatures zipping around the water. In about 1-3 days, the adult mosquito emerges from the water’s surface, dries its wings for a few minutes, then flies off to find you and your family to feed on.
Use BTi “dunks” to create proactive mosquito traps
Mosquito dunks are small disks that look like cookies…cookies of mosquito destruction! They contain bacillus thuringiensis israelensis (Bti) naturally occurring bacteria found in soil and stagnant water. When the dunks are added to standing water, they slowly release the bacteria spores into the water, which are then ingested by mosquito larvae. Dunks continue working for up to 30 days.
The science behind it is that the bacteria produces toxic proteins that are only activated inside the gut of certain insect larvae, those with the right alkaline pH and the specific receptors to match the toxins. These insects are all members of the fly family (Diptera), like mosquitoes, blackflies, and fungus gnats. They do not affect birds, mammals, fish, amphibians, bees, butterflies, dragonflies, or any adult insect (including adult mosquitoes!). Once activated, these highly targeted proteins poke holes through the gut lining of the larvae, causing them to stop feeding and die within 24-48 hours. Boom goes the mosquito dynamite!
You can break a dunk into pieces and place it in pre-existing standing water like rain barrels, birdbaths, planter saucers, ponds, or eavestroughs. Or, go full assassin and control reproduction by proactively building mosquito traps and adding standing water with dunks to your property!
Dragonflies are your secret weapon of mass mosquito destruction
Don’t fight the river. Ottawa is a city built on wetlands. We will never be rid of mosquitoes, but we can manage their impact by tipping the wetland ecosystem in our favour.
A single dragonfly can eat up to 100 mosquitoes a day. Adult dragonflies can travel several kilometers from their aquatic birthplace in search of prey and territory. Because of our proximity to the river, you don’t even need a water source in your yard to take advantage of these highly effective mosquito eating machines. They will patrol your backyard if you give them a reason to. Here’s how to turn your garden into a dragonfly stronghold and let nature take care of mosquito control:
1. Give Dragonflies Places to Perch
Dragonflies are visual hunters. They like to perch from a high vantage point to scan for mosquitoes. Add bamboo stakes sticking straight up out of the ground, plant supports, tomato cages, or trellises in sunny spots. Plant tall native flowers like Joe-Pye Weed, Blue Vervain, or Ironweed. Add trellis cables or lines of string over your garden, 7-10 feet above ground. Keep in mind that birds eat dragonflies, so they need hiding spots like large plants to feel safe in your yard.
2. Create Insect-Rich Hunting Grounds
Dragonflies eat more than mosquitoes: they also consume gnats, midges, and small flies.
Growing native plants significantly increases the insect biodiversity of your yard and attracts bees, butterflies, and other pest hunting insects. Your garden will buzz with life.
3. Provide Water or Wet Zones
Even though the Ottawa River is nearby, a small yard-level pond can encourage dragonflies to linger, mate, and lay eggs. Adding a mini wildlife pond (no fish) or even a shallow basin with aquatic plants is enough to draw dragonflies in to stay for a while. Moisture-loving plants like Monkeyflower, Blue Lobelia, or Swamp Milkweed create micro-wetlands without a formal pond.
4. Offer Sun & Airflow
Dragonflies need warm, open, sunny spaces. They’re cold-blooded so the warmer the yard, the better their metabolism—and mosquito hunting. Place perches in south-facing, sun-filled, wind-protected areas.
If you invite dragonflies in, they will take care of business, for you and your neighbours!
Protecting biodiversity fights climate change (no, actually)
A biodiverse yard can handle droughts better, recover faster from heatwaves, and support pollinators that keep your food system going.
Meanwhile, monocultures (like grass lawns or pesticide-treated gardens) collapse under stress—making climate extremes even worse. In fact, dead zones—like sprayed lawns or degraded soil—don’t just stop storing carbon… they can start releasing it.
Nature works like a team. When you remove players—like insects, frogs, or native plants—the system weakens. Climate change hits harder, and nature can’t bounce back as easily. It may feel like what we do, as individuals, doesn’t really matter, but every square foot of habitat you create is an oasis in the desert for so many species.
Spraying for mosquitoes may seem harmless—but every time we lose bees, dragonflies, or birds, we weaken nature’s ability to defend us from climate change. The more species we protect, the more stable and self-healing our world becomes.
