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.