Does a hard winter kill off insect pests?
Every time there is a particularly cold winter with a lot of below-freezing temperatures, one comment I hear is from folks hoping at least it will kill off the bad bugs.
By the same token, when the winter is especially mild, people are heard to say they are dreading a bad year for bugs because of a lack of freezing weather.
I did some looking around and, not surprisingly, I found that the theory doesn’t hold water. What they say about roaches seems to be true for most insects: they are highly resilient and can survive extreme conditions.
They have three basic survival strategies:
1. Avoid the cold
This means that the insects either shelter or migrate. They take shelter deep in the soil, leaf litter, beneath tree bark or in decaying logs where it is several degrees warmer. They can also migrate to warmer areas just like birds.
2. Chemical change
Some bugs produce chemicals in their bodies that keep them from freezing even when the temperature is below freezing, sort of a natural antifreeze.
3. Freeze safely
Other insects can freeze, but they have certain proteins that protect their tissues and minimize bodily damage caused by freezing.
Well, it had to be too good to be true, didn’t it?
After all we only have to remember that regions with super-cold winters like Alaska have pesky insect populations to give up on the hope that an atypically harsh winter is no guarantee of a bug-break once the weather warms up.
Anecdotally, I can report finding a tick last month, yes, a tick this February, despite record-breaking cold. It was one warmish day and we were all out in the yard. The kids got mosquito bites, too. A few days later it was back in single-digits and we were shivering and scratching mosquito bites at the same time.
Of course, some insects are kept at bay by extreme cold, but it usually takes more than one would think. To reduce numbers of fire ant colonies, for example, it takes two weeks of below ten degrees (F). Some mosquitoes are able to hibernate, and mosquito eggs can survive being frozen.
Weather event that does have a significant effect on insect populations? Drought.
As a gardener, I’m putting all this in the not-fair category.
Take heart- a recent study from Virginia (I think) showed a dramatic reduction in stink bug numbers following polar vortex temperatures. Some of those garden pests do seem to be damaged by the cold. Unfortunately it doesn’t include ticks or mosquitoes.
I did hear reports that the cold winter has helped kill off some portion of non-native, invasive insects. One scientist estimated that the excessive cold had killed off up to 80% of the emerald ash borer population in Minnesota.
For mosquitoes, I’ve heard that it’s a lighter season when we have a few weeks of warm weather in the spring (enough that a good portion of the eggs start hatching) followed by a few days or so of below-freezing temperatures, which will kill the less-resilient full-grown mosquitoes.
I am a veterinarian in Oklahoma. This winter my children have missed mucho school due to freezing/snowing/sleeting/what-have-you. I have also seen TICKS, FLEAS, ALLERGIES, and PARVO (look it up–nasty business) by the truckloads. These are supposed to be SPRING problems!!! The only thing I haven’t seen is snake-bites. Crazy, crazy weather! Hardy bugs. 🙁
ps–I saw some mosquitoes one day after the temp finally rose from 24 to 45 and the water melted. Forty-five degrees!!!
I’m in Connecticut where we constantly deal with ticks, Lyme disease, and other tick diseases. (Lyme Disease was actually named after Lyme, CT where kids kept coming down with a mysterious illness, later to be called Lyme disease.) I’ve had Lyme, my dog had been treated 3 times for it, and members of my family have had various tick diseases. I hate using chemicals on my family and pets to deter ticks, but I think it comes down to weighing what’s worse. I always find a much bigger problem with ticks around the fall frost- they are looking for a warm host for the winter.
Katie & Erin–Have y’all ever heard of or tried the method of tick control where you soak dryer lint with pyrethrin spray, let it dry and tuck it into toilet paper tubes you leave around the yard to be gathered by tick carriers for bedding in their nests and dens? It’s supposed to kill the ticks on the hosts and break the chain of transmission to humans. I wonder if it works?
Nice article!!! I always suspected that there wasn’t much truth to hard winters killing off bugs! But I sure do get that question a lot!! Looks like we will need to continue to learn natural, safe ways to stay a step ahead of the bugs!! I’m game, I like the challenge!!!
Thanks again!
It will totally depend on the insect. Their defenses have fairly precise points below which they perish. The timing of the cold matters a great deal as well, as it has to happen when they will be susceptible to it, and has to last long enough to overcome their defenses.
Source: I’m a biologist in Northern Canada 😉