Why do mosquitoes lay their eggs on water?

Because there's a mosquito life cycle... it starts of with an egg and then it lays its eggs in the water because the egg hatches in to a larva which comes to the surface to breath. The Larva eats micro organisms in the water then later on sheds its skin 4 times... and grows bigger. The it turns into a Pupa which is an undeveloped adult mosquito. it takes two days for it to fully become an adult. The skin splits and it emerges as an adult.