WASHINGTON — It’s getting colder, bringing colorful leaves, spooky decorations, and *hopefully* the end of the mosquito season. Yet while there might not be as many mosquitoes flying around this season, some people are still getting devoured despite the chilly nights. So, what’s going on?
THE QUESTION:
Does cold weather really kill mosquitoes?
THE SOURCES:
THE ANSWER:
Some mosquitoes tend to die in cold weather, but many enter a state of hibernation that allows them to survive the winter.
WHAT WE FOUND:
First off, it’s true that mosquitoes aren’t able to fly around once it gets cold. Like snakes and other cold-blooded animals, mosquitoes can't actually self-regulate their internal temperature.
"Their body temperature depends on the surrounding environment," Lill said. "So when it reaches some critically low temperature, they can’t actually move.”
Unfortunately for humans, mosquitoes have a few strategies to deal with the cold. Some species can't survive the winter as adults, so instead they've adapted to ensure the survival of the next generation. When temperatures start dropping, these mosquitoes lay eggs in the ground that will only hatch when temperatures start to rise again.
However, many species can hibernate, becoming inactive and slowing down their metabolism in a state known as quiescence or diapause. In these cases, mosquitoes can stick around well into the fall as they stock up on food for the winter. According to Dr. Markowski, “most of them will want to take that final blood meal and then overwinter as a blood-fed female, and then they'll lay their eggs as soon as the weather warms up in the spring.”
Those "blood fed females" are probably the source of any mosquito bites you get later in the Fall. So, even though mosquitoes are less of a nuisance during the colder months, it’s not necessarily because they’re dead. Dr. Markowski notes that once mosquitoes have prepared for the winter, they’re quite resilient.
“Once they go down… it can get as cold as it wants out," Markowski said. "There can be five feet of snow on top of them, they don’t really care, they’re dormant.”
In fact, Markowski says consistent cold isn't as bad for mosquitos as cycles of warm and cold days that keep waking them up throughout the winter. Waking up burns energy, and if it happens often enough, it can be deadly for the insects.
So, sorry to kill your dreams, but we can verify that, no, cold weather doesn’t kill all mosquitoes.
But, there won’t be many around to bite you… not until spring anyway.