 The major objectives are improving fecundity (the egg-laying capacity of a breed), the health of larvae, quantity of cocoon and silk production, and disease resistance.Healthy larvae lead to a healthy cocoon crop.Health is dependent on factors such as better pupation rate, fewer dead larvae in the mountage, shorter larval duration (this lessens the chance of infection) and bluish-tinged fifth-instar larvae (which are healthier than the reddish-brown ones).