In the UK we have just experienced the warmest Halloween ever to be recorded, and at a delightful 23.6 C in Kent, we sailed past the previous record on of 20C[1]. Whilst it is a luxury to be able to grace the beaches in little more than a t-shirt and cardigan at the end of October, sadly there are knock-on effects. This week, not only have we felt the harsh bite of reality as temperatures drop by 10 degrees over night, but it also means hibernation time of the mosquito.
Mosquitoes are cold-blooded and prefer temperatures over 80 degrees. At temperatures less than 50 degrees they shut down for winter, many of which find shelter in dark h
oles, basements and the like to wait for the warm weather to return.[2] While others lay eggs in preparation for the hotter climates so that the by the time they do, the next generation of mosquitoes are ready to rise.
It is pretty hard to believe that these fragile-looking creatures can survive freezing temperatures, but hibernation is actually the most common tactic of the mosquito to survive the colder months, rather than simply dying out. Many species of mosquito have an anti-freeze chemical in their blood that ensures the cell walls to not rupture when the ice sets it.
J. Turner Brakeley, who owned a cranberry plantation in New Jersey, became fascinated around the turn of the 20th century with studying mosquitoes, particularly their actions in the cold. He worked hard at making observations and sending them to entomologists who catalogued and published his findings.[3] Perhaps the most interesting of his findings was the discovery of a new species with a unique cold-weather survival strategy, the pitcher-plant mosquito (Wyeomyia smithii) spends the winter frozen in the ice trapped in the leaves of the pitcher plant for protection.[4]
Upon their discovery Brakeley noticed the larvae frozen in solid ice inside the leaves of the pitcher plants, after the temperature had been two degrees below zero. He brought them indoors and let the water melt and sure enough, soon after he reported that they begin to move.
The Aedes Communis, or more commonly known as the snow or snowpool mosquito, exclusively lives in the northern United States at high elevations, where it uses early spring pools in otherwise snow-covered forests to raise its larvae. The adult mosquitoes don’t live over the winter, but the eggs that they lay in the Autumn hatch and develop into larvae so early that the new adults will be flying while snow is on the ground, even though other species may still be hibernating. Their scaly brown or black bodies enable them to brave the tougher conditions, but luckily the female snow mosquito is more inclined to bite birds and mammals, rather than humans.[5]
Now all this talk of mosquito hibernation and disappearing for a few months can only be a good thing? Well indeed it is, however, there is a period of time where the weather declines and although a lot of mosquitoes are dying off, the ones planning to hibernate are about to take their final blood meal. As they don’t totally disappear until temperatures are consistently freezing, now is the time to be taking most precaution to prevent you becoming their final blood meal – especially if you travel on the London Underground! As I have stated many times before, when there is rainfall combined with mild weather, there will be mosquitoes about and there is a chance that you will be bitten. So what can you do?
As there is a smaller mosquito density at the moment, swapping your incognito® spray for the moisturiser means that you are getting sufficient protection as well as preparing your skin for the colder temperatures.
Sources
[1] “Warmest UK Halloween on Record.” BBC News. BBC, 31 Oct. 2014. Web.
[2] 33 Things You Didn’t Know About Mosquitoes.” Mosquito Facts – 33 Things You Didn’t Know About Mosquitoes.Web.
[3, 4, 5] Miller, Elizabeth. “Where Do Mosquitoes Go in the Cold?” Where Do Mosquitoes Go in the Cold? Mosquito Reviews, Web.