Citrus Gall Wasps go through a life cycle of complete metamorphosis: egg, larva, pupa, adult. All stages of this life cycle, except the adult stage, occur within the woody gall on the citrus plant. There is only one generation per year.
Adult citrus gall wasps emerge from their woody galls during spring. In south-eastern Queensland and north-eastern New South Wales emergence occurs from mid-September to early November. In southern Australia emergence occurs sometime between mid-October and mid-December depending on the climate.
The wasps mate, and females begin laying eggs on the same day as emergence. Female wasps lay their eggs into the bark of soft new growth twigs. They are capable of laying about 100 eggs over their life of about two weeks. Several females may lay their eggs into the same twig at the same time.
Eggs hatch after about two weeks and the larvae burrow into the bark. A sheath of soft tissue develops around the larva initially, but by late December woody tissue begins to form. Then the twig swells and begins to develop the characteristic gall. Large galls may contain hundreds of larvae.
Larvae live inside this gall in individual cells for several months, after which they pupate, and eventually emerge as adults the following spring. Emerging wasps leave characteristic pinprick size holes in the woody galls. Citrus Gall Wasps are poor fliers and short lived so they mate and begin egg laying almost immediately, often into the same tree.