Females mate only once in nature, while males can mate several times. This can be explained by the competing pressures that each sex faces. wood white males would need to mate with as many conspecific females as possible to maximize the number of viable offspring, while females benefit from only mating once, since the egg-laying process of choosing the best food-plant on which to oviposit is so time and energy intensive—mating multiple times would not be a good use of resources.