Caleb is a forensic entomologist gathering evidence at a crime scene. How can he determine the stage the maggot larva has reached? Caleb is a forensic entomologist gathering evidence at a crime scene. From the victim’s mouth, he retrieves maggots that are in the BLANK , which is the stage maggots reach directly after hatching. He can determine the stage of the maggot larva based on the BLANK and the BLANK of the larva.