Adults use their exodont mandibles to break free of the tough host puparium. The pupae is without a puparium. The Alysiinae larva then pupates within the host puparium. It mates shortly after emerging from its winter state as a puparium. The pupa is enclosed within a puparium. The change in colour of the puparium can determine the age of the pupa. The larvae pupates in autumn, forming a black puparium. After three larval instars, the white prepupa immediately forms a hard, dark puparium. Then the larva immediately burrows into dry sandy soil to pupate within a protective puparium. After completing pupation, the adult fly breaks out of the puparium. Oviposition is into the egg or larva and emergence is from the puparium. Ecdysone and 20-hydroxyecdysone regulate larval molts, onset of puparium formation, and metamorphosis. A new adult emerges from the puparium after a complete metamorphosis. The pupa also has a hard case on its outside called the puparium. The dark-brown coloured puparium is formed from the hardened last larval skin.