 The optimal mating time for females is on the same day they emerge, because fertility decreases when mating occurs later.Females release pheromones as a type of calling behavior to demonstrate to males when they are most fertile.In a study of the effects of food shortage and larval crowding on male reproductive phenotype, it was found that males who emerged as adults from the population with the most crowding had smaller forewings, thorax, and head, as well as a lower body mass.