Blowflies are usually found near decaying material. Adult blowflies deposit their eggs in the decaying material. Carcasses of dead animals are the locations that they prefer. Many times people find blowflies in the home. This often happens when the flies discover a dead squirrel, mouse, or bird that the homeowner had not seen.
Around homes, the garbage cans are also favorite blowfly breeding sites. The flies will also deposit their eggs in animal droppings. Some blowflies will enter homes. If meat or other food it exposed, the flies will even deposit their eggs in it.
When they come out of their eggs, blowfly maggots begin to eat the material where they hatched. They do not have eyes or legs, so they cannot travel to other foods.
As they grow, the maggots burrow down into the material. Depending on the species, the blowfly maggots can finish their larva stage in as little as two weeks. However, for some species, the larva stage can last as long as a month.
As they grow, blowfly maggots must shed their skin two or three times. When they are fully grown, the maggots can be almost one inch long. They are whitish in color. The body is tapered with the wide end toward the rear. There is a pair of dark hooks at the head-end of the body.
In the last part of the larva stage, the maggots crawl out of the food material where they have been living. They burrow into the soil where they change into adult flies. Larvae that develop late in the summer often spend the winter as maggots or in their pupal case.
Scientists have discovered a way that blowfly maggots can actually be beneficial to humans. Some species of blowfly maggots are used as “surgical maggots”. Doctors use specially grown maggots to clean infected wounds. The maggots remove the infection and cause the wounds to heal faster than they would otherwise.