Do Mosquitoes Poop and Pee?

Do Mosquitoes Poop and Pee? Of course, mosquitoes, like all animals, must eat and therefore excrete waste material. The feces of a mosquito is so tiny, however, that it is very difficult for the human eye to see. When a female mosquito is sucking blood from a host, she will often excrete a watery substance that is sometimes mistaken as urine. This liquid is not urine, however, but is instead the liquid portion of the blood that she is eliminating in order to make more room for the solid portion of the blood that has more protein and nutrition.