It is a complex system in which six needles are used, blood is anticoagulated and water is removed from blood to concentrate it as a food source for the larvae it will feed: - https://aeon.co/videos/what-makes-mosquitoes-so-good-at-getting-under-our-skin?utm_sour... - This is an irreducibly complex mechanism. It is a saltation by definition. It cannot develop bit by bit.