Mosquito Bites: Can lots of mosquitoes sucking our blood make us weak? All mosquitoes don't suck blood!! It may surprise people to learn that adult male and female mosquitoes feed on nectar as a food source, while larvae survive on plant and animal matter in water. It is only the female that will bite humans to obtain a blood meal, which she uses to produce eggs. Why do mosquitoes suck our blood? Adult female mosquitoes bite hosts to get the protein they need to produce and lay eggs.Female mosquitoes have a mouthpart made to pierce skin and siphon off blood. As a biting mosquito fills itself with blood, it injects saliva into your skin. Proteins in the saliva trigger a mild immune system reaction that results in the characteristic itching and bump. Males lack this blood-sucking ability because they don't produce eggs and so have no need for protein in blood. Male mosquito feeding on nectar How much blood do we lose?