substage of immediately preceded by developmental stage prepupal stage prepupal stage P3 prepupal stage P4 pupal stage P4 FlyBase_development_CV cryptocephalic pupa FBdv:00005346 Temporal ordering number - 540. Prepupal stage P4 begins as the lateral trunk trachea become obscured and ends when the imaginal head sac is everted and the oral armature of the larva is expelled. Duration at 25 degrees C: approximately 5 hours, 30 minutes. (126.75-132.2 hours after egg laying; 6.75-12.2 hours after puparium formation).