During mating, male mosquitoes transfer signals to the female that block her from mating with other males. This ensures that he is the father of all of her offspring. These signals can also be used in competition between two species when males of one species block females from mating with males of their own species thus preventing them from successfully reproducing. We aim to identify signals transferred from the male to the female, determine which receptors they activate in the female, and ask how interspecies competition may affect these receptors. The molecules that we discover could be used to develop new ways to control mosquito populations.