Mosquitoes under floor boards in UK???

Found under my floor.
Mon, Nov 24, 2008 at 3:38 PM
I am busy doing some house renovations and on lifting some of my floor boards I found about 2-3 dozen of these critters standing on the under side of the floor boards. They seem reasonably inactive, most of them are just stood there, 1 or 2 are flying around. Since then I have also spotted 2-3 flying round in the rooms of the house. The conditions under the floor boards are cold and damp, bare soil is present.
I am on the North East coast of the UK, and it is a fairly wet and cold mid November at the minute.
The reason for wanting to know what they are is mild concern that they may be the adult form of something detrimental to wood.
Overall length of the body is around 9-10mm, as scale isn’t clear in the pics.
Cheers, Cam.
North East UK

Mosquito from UK
Mosquito from UK

Hi Cam,
These sure look like Mosquitoes to us, but we can’t figure out what they are doing under the floor boards. Perhaps there is a stagnant water source nearby where they are developing. Perhaps one of our readers can share some insight. The Mosquitoes won’t harm your floor, but the females may bite you and your family and tropical species especially are important disease vectors.

Mosquito from UK
Mosquito from UK

Hi, Daniel:
Wow, you have been very busy posting!  I turn my back for a week and….wham!  LOL!
Ok, the mosquitoes may be overwintering as adults, don’t know.  Just contact someone locally in L.A. in vector control at the public health department for a better explanation.  Mosquitoes I don’t know that much about, honestly….

Correction Courtesy of Angel van Gulik:  January 17, 2017
This one is most likely a Culex pipiens.  The shape and coloration of the abdomen, along with indoor overwintering behavior is typical of that species, and it is the most common mosquito found in England.  I can’t ID to 100% certainty only because I would have to view the white “stripes” on the abdomen very closely to see whether they come to a pinch along the edge or not to rule out Culex salinarious.

2 thoughts on “Mosquitoes under floor boards in UK???”

  1. They might be Chironomids too. According to BugGuide, “Larvae of most midges are aquatic; a few occur in decaying matter, under bark or in moist ground.” The floorboards sound like an ideal habitat for those latter few.

    For Cam’s sake I hope they’re midges (which don’t bite). I wouldn’t want all those mosquitoes in my house!

  2. Hello Cam:

    They definitely look like female mosquitoes. In Canada our winters are little colder than in the UK and most adult mosquitoes die after the first hard autumn frost. However, late hatching adults in a number of species do overwinter by crawling into protected hiding places, including cold attics or basements if they can find a way in, and going into a state of torpor. They will also hide under loose bark, for example in a stack of firewood, and we occasional find a few flying around indoors in the dead of winter after hauling in some wood for the wood stove. Cheers. KK


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