I was honestly wondering why we haven't seen a mosquito girl before, too. You can have fun with this idea. They are kind of like vampires that only give their victims temporary itchy little bumps instead of transforming them into soulless undead monsters. It's all the ghoulish fun with a tiny fraction of the evil!
EDIT: Well, until malaria gets involved, that is.
I was honestly wondering why we haven't seen a mosquito girl before, too. You can have fun with thi