The London Underground Mosquito

Who would have guessed that the London Underground is home to a unique species of mosquito? The species is called the London Underground mosquito and is thought to have evolved from Culex pipiens. The London Underground species has been called Culex pipiens molestus, because it is a vigorous biter.



It is not new, but it is comparatively new in biological terms. Molestus is known to have bitten Londoners during the Second World War while they were taking refuge during the air raids. However, there are other references to a mosquito with the same name, molestus, 170 years before the war, when there was no underground railway system in London or anywhere else in the world.



This mosquito was first discovered in the London Underground, which is why it received its name, but it can be found in metro and underground railway systems all over the world.

No one really knows a lot concerning this insect population yet.



Some people suggest that it is a variant of a local Culex pipiens that has adapted to living in warmer, underground tunnels, while others say that is a southern (and therefore warmer) variant of C. pipiens that is able to live in the colder north because it has colonized the warm train tunnels of the underground railways.



Yet others, notably Kate Byrne and Richard Nichols, propose that it is a totally separate species from Culex pipiens. Their proof for saying this is that there are differences between pipiens and molestus: they display very different behavioural patterns and do not mate readily with one other.



C. pipiens molestus will bite rats, mice and humans and dies in cold temperatures but stays active all year round, whereas C. pipiens can tolerate cold weather, only bites birds and hibernates if the weather gets too cold.



On the rare occasions when the two species cross breed, the eggs are infertile, which implies that they are distantly related if at all. Recent studies suggest that molestus originated in one source but spread rapidly throughout the world, perhaps in freight.



Second-hand tyres have been held responsible for spreading molestus throughout the world. There is a huge international trade in second hand tyres and it is notoriously problematic to get all the water out of a tyre that has been left in the rain. Mosquitoes can breed in a minuscule amount of water, so this is a possibility.



There is a bizarre and not entirely explained twist to the story of the molestus, the American version of molestus pipiens still bites birds which leads some people to say that molestus is a separate species, but that it has formed a hybrid in America with pipiens.



This is fairly frightening, but fairly possible, because the American pipiens can transmit human encephalitis caused by the West Nile virus, an outbreak of which hit New York in 1999.



There is a lot more to find out concerning the London Underground mosquito, since the story is only just beginning to unfold. The real story will almost certainly come out of America where this new mosquito has proved to be the most perilous.



Owen Jones, the author of this piece writes on a number of topics, but is currently involved with finding a home remededy for mosquito bites. If you would like to know more, please go to our website at Getting Rid of Mosquito Bites.