- The blow fly is highly valued in the scientific world. By studying the blow fly's life cycle, a scientist can determine the post-mortem interval, or time of death, of a body at a crime scene or of an animal in the wild. A scientist can use the blow fly to determine whether the animal or human was healthy at death, and even whether the body was moved post-mortem. Blow flies appear on the scene soon after death and lay their eggs in areas where the trauma occurred, such as bruises and abrasions. Eggs are also laid in the mouth, ears and nose. Blow fly eggs are tubular in shape and are laid in large groups. Blow fly larvae are typically white, and hatch directly from the egg. Known as "maggots," blow fly larvae are cone-shaped, with a mouth at one end that contains hook-shaped features that allow the maggot to attach itself to the host. The hooks also serve to assist in locomotion. Their bodies are segmented, and maggots will shed their skin three times during this stage of their life. Each time the skin is shed, the larvae gains a large mouth opening with larger mouth hooks.
- The third time the skin is shed, it actually shrinks and hardens. Inside this hardened shell, the larva molts and gains its wings and traditional "fly" shape. The skin itself retains the same visible characteristics as the previous larval skin, and the same segmented appearance. While the newly-minted fly pupa inside the casing does have wings, it is essentially motionless and lacks the ability to move, feed or defend itself.
- When it first emerges, the adult blow fly is very soft and vulnerable. This is the most dangerous time for the newly hatched adult fly. Because the wings are non-functional and the fly has very little color, it is unable to camouflage or evade predators. However, once the body hardens, after approximately 48 hours, it is able to move fully and is ready to mate. Adult flies will mate frequently, and may travel for dozens of miles before finally laying their eggs on a fresh medium.
