The larval lifestage has a variable duration, generally 20 to 30 days, and the larva must rely on stored resources during this time. The importance of the richness of blood to this development can be seen, since all tsetse development before it emerges from the puparial case as a full adult occurs without feeding, based only on nutritional resources provided by the female parent. The female must get enough energy for her needs, for the needs of her developing offspring, and for the stored resources which her offspring will require until it emerges as an adult.