The Surprising Purposes of Blowflies

For most of us, blowflies are a nuisance we do our utmost to be rid of. In fact, there is a whole industry built around removing them from our environments. Willing to do whatever it takes, we buy traps, fly swatters, and screens to keep them away from our porches and outside of our homes. Because flies can carry bacterial diseases such as dysentery, cholera, and typhus, it actually is a good idea to keep them away from ourselves and our pets. However, it would be to our detriment if we did away with them completely for they play a vital role in the life cycle of our planet.

Blowflies Play an Important Role in the Decomposition Process

Blowflies are a type of fly that lay their eggs in dung, rotting meat, or open wounds. When the eggs then hatch, the resulting larvae feed on the surrounding materials and through the larvae’s digestive system, materials are broken down into their components and the nutrients are returned to the soil. Without the blowflies breaking down waste and dead carcasses, this decomposition process would take far longer and our world would have far more rotting carcasses lying around spreading disease. Thus, as annoying as these flies can be, they help make that final connection in the life cycle from death to birth of new life.

The Life Cycle of a Blowfly Can Tell Us the Time of Death

Whenever the police investigate a death, one of the most important pieces of evidence is determining the time someone died. Not only is this important in figuring out how someone passed, but it can also determine who killed them if crime was involved.

Sometimes a body is found more than 72 hours after death. At this point, usual indicators of time of death including skin color, body temperature, and degree of muscle stiffness have all abated. This is where blowflies come in handy. A blowfly will lay eggs on a dead body as soon as a few minutes after death. If detectives can determine which species of blowfly is present on the body, they can investigate what life cycle stage the blow fly is in, compare it to that specie’s growth timeline, and know how long it’s been there.

Though there are many species of blowflies that grow at different rates, the general life cycle from egg to adult fly is the same across the board.

6 Main Stages of the Life Cycle of the Blowfly

1. Adult Blowfly Lays Eggs

An adult female blowfly travels around finding a place to lay her eggs. The perfect spot is an open hole in a carcass such as in a wound, mouth, anus, eyes, nostrils, or ears so the resulting larvae has a place to feed when it hatches.

2. Hatching of Eggs

Most blowfly eggs are between 1-2 mm long and typically take 24-45 hours after being laid to hatch.

3. 1st Stage Larvae/Maggots

Once eggs hatch, the blowflies are known as first stage larvae, more commonly known a maggots. These larvae produce an enzyme to break down the protein surrounding them so they can feed on the semi-liquid bodily fluids. As the larvae helps the body decompose in this way, they grow and are ready to shed their first exoskeleton after a few days.

4. 2nd Stage Larvae/Maggots

Once the first exoskeleton is shed, the larvae enter the second stage. Here they continue to grow in size as they enzyme breaks down the body and they feed on the resulting material. When they are big enough, they molt their exoskeleton for a second time.

5. 3rd Stage Larvae/Maggots

After the blowfly sheds the second exoskeleton, they are now called pupae and are in the third stage of their growth as maggots. They then find their way to the ground and no longer move or feed. While they lay there, their last exoskeleton hardens and gradually turns from a light brown to a black color.

6. Adult Blowfly

Once the exoskeleton has fully hardened, the adult blowfly emerges from inside and can fly after only a couple of hours. Once they have reached this final stage, a male blowfly can mate with a female right away. The female, however, must feed on some additional protein such as another carcass or feces before she has the nourishment she needs to lay eggs of her own.

With this knowledge of a blowfly’s life cycle, in addition to the specific timelines of growth for types of blowflies, detectives and scientists can convict people of violent crimes and give answers to the families who need them. Though the look of maggots on a decomposing body can look disgusting, they are a vital part of an investigation as well as the life cycle of our planet.