The pesky mosquito

Question....what use do mosquitoes have in the world, apart from annoying people, biting them, and then causing them to itch for the next couple of days? Before I came to Japan I had never had a mosquito bite in my life. After 2 months here I received my first bite, the little pests haven't stopped since! Just one mosquito gave me about 8 bites last night...and it's October! Gaaaah! Well I hope it had a nice feast, cos it's the last one it will have. I will track that mozzy down before bed tonight, and I will kill it with my super-sonic spray! There are very few things I absolutely hate in life, but the mosquito is definitely heading for the top of the list!