Blowfly pupa. Macrophotograph of a pupa of the blowfly Calliphora erythrocephala. The red pupal case has hardened around the larval maggot (head at top), and a nymph of the blowfly will begin to form. Metamorphosis of the blowfly begins with eggs laid on a food source, such as rotting vegetation or animal flesh. Eggs hatch into the white maggot within a day, and the maggots pupate in 3-4 days; from pupa to emergence of the adult fly takes 3-5 days. The adult, also known as a bluebottle fly, lives some 2 months and is considered a domestic pest.