What are the most active pests in heatwaves?

When the weather heats up, humans aren’t the only ones trying to cool down by searching for shady shelter and flocking to water to stay hydrated. Insects, which are cold blooded creatures, are especially susceptible to heat waves and homeowners might find that they have more parasites and pests than usual during prolonged hot and humid weather.

In this article, the pest prevention and management specialists at Extermination Leblanc share their insights about which insects become most active during heat waves in the Montreal, Montérégie and Estrie regions of Quebec. If you are concerned about an insect infestation, reach out – our experienced exterminators can help you get rid of the pests immediately and take measures to prevent future outbreaks, as well.

Here is what you should know about the most active parasites and pests in heatwaves.


Let’s start with the good news first! Mosquitoes do not tend to thrive during dry heat waves and you might find that you have fewer mosquitoes than usual during prolonged periods of hot, dry weather. This is because the shallow pools and puddles of water where they breed might be dried up.

But as soon as the humidity returns and temperatures fall back into a more comfortable range, below 26 degrees Celsius, in this case, mosquito colonies take little time to bounce back and it will be open biting season again.


Heat waves have a dramatic impact on how earwigs behave, and it all centres around their relentless search for water. It is very common to find more earwigs in our homes during heat waves due to the lack of moisture in the ground outside. To make matters worse, a higher number of eggs and young are able to survive during warm, humid weather, which means there could be even more of these pests trying to get into your homes in search of water during a heatwave.

Be extra vigilant about keeping hanging damp towels and clothing up to dry and deal with any sources of water or moisture that might be accumulating in the kitchen, washrooms, or basement.


Much like earwigs, ants are also affected by the lack of moisture in the ground during heatwaves and might choose to search for water in your home. Added food sources like overripe fruit and wilting vegetables can be another thing that attracts ants into our homes during heat waves.

The same advice applies for trying to control the number of ants that march in and out of your home during the hot summer months: eliminating food and water sources is the first step to controlling an infestation.


Houseflies are always more numerous when there are heat waves due to the fact that their eggs hatch more than 2xs faster in high temperatures. Normally, house fly eggs hatch into larvae in 20 hours. Turn up the outdoor heat to 37 degrees Celsius or higher, and the eggs are now turning into maggots in less than 8 hours.

Give it another four days of heat, and those maggots will be mature adult flies buzzing around your home. Considering that each female fly can lay up to 900 eggs in her short 21 day lifespan, the potential for fly infestations is understandably real.

Sealing garbage cans tightly in heat waves is a simple and effective way to help lower the fly population because this is where eggs are often laid and grow into maggots before turning into flies.

Wasps, hornets & yellowjackets

The lack of water and moisture during heat waves will cause wasp, hornet, and yellowjacket populations to become more agitated and aggressive. This alone means that there is an increased risk of bee stings during heat waves. Added to this increased risk is the fact that yellowjacket nests can double in size in less than a week during hot weather.

If the heat wave persists and we experience a particularly hot summer, yellowjacket nets can continue to grow into the 1000s throughout the summer. For this reason, if you see a nest forming in an area where you and your family will be spending time (for example near an entrance or on your patio), it is best to deal with the nest early on before it grows even larger.

We’re here to help

If you are experiencing a parasite infestation and need help to deal with the uncontrolled number of insects in your home or on your property, reach out to Extermination Leblanc today!

We are the insect extermination experts serving the Montreal, Montérégie and Estrie regions and can find the right solution for your pest problem. We use only Health Canada approved substances and take the safety of you, your family, and your pets very seriously. Give us a call today for a free estimate.