How do mosquitoes know when it's night time?
How do mosquitos know when it's night time? Even if the light is on they still insist on biting and biting! AAAAARG!
Well mosquitoes have a body clock just like we do.
They have a cluster of nerve cells in the mosquito nervous system which use a genetic "domino effect" to keep time. So one gene turns on, turns another one on, which turns the first one off and turns the third one on, and so on.
This changes the behaviour of the nerve cell, which in turn then changes the behaviour of the whole organism.
In fact, this is a phenomenon that was first picked up in the 1970s. I've got the paper here: Journal of Experimental Biology, "The Circadian Rhythm of Flight Activity of the Mosquito Anopheles gambiae, the Light Response Rhythm." by D.R. Jones, C.M. Cubbin, D. Marsh from Brunel University. 1972, that paper was published.
They found that mosquitoes have a body clock just like us and you can jet lag them. So, basically, it's their instinct, just like mice and other nocturnal animals use their body clock to wake them up at night to come and find food.
It's the best time for Anopheles mosquitoes to come out at night, that's when their body clock wakes them up.
But, not all mosquitoes are the same. There are some mosquito species that are active during the day but they are not active at night, and I'm thinking of a good example of this is Aedes aegypti mosquitoes. They're big, hungry mosquitoes. They spread things like dengue virus and they're a real pest because, even if you use a mosquito net, you can't protect yourself because they bite people lots of times during the day, so you find it much harder to ward off their attacks.