All the larval stages of navel orangeworm can cause serious damage to many fruits like oranges, figs, apples, pears and peaches. Then can also cause damage to nuts such as almonds, pistachios and walnuts. First stage larvae of navel orangeworm begins feeding on the nut kernel. As these larvae grow up to their fourth stage, they completely destroy nuts. While feeding, larvae can spin silk web at feeding site and leave lots of frass. Injuries caused by larval feeding can serve as entry points for disease causing organisms.
Navel orangeworm overwinter as larvae inside the rotted oranges or mummy nuts and fruits on the trees or on the ground in hullers. When temperature warm up in March, these larvae will pupate in the ground. Adults will start emerging from these pupae in late May. Then, mated females then lay eggs singly on the surface of the mummy nuts. Eggs hatch into small larvae that enter into the nutmeat and start feeding on the nut then mature and life cycle continues. When conditions are right, navel orangeworms can complete 2- 4 generations in a year.