Flies Life Cycle
The life cycle of flies is the same as that of insects in general, going through four 4 stages. Starting from laying eggs, larvae, pupae, and adult flies.
A fly generally lays eggs where it hatches into larvae that can immediately forage for food. Usually female flies will choose to lay their eggs in the same place where flies live in general, such as livestock manure or garbage.
After the eggs hatch, they come out as larvae or commonly referred to as maggots. Larvae or maggots are worm-like creatures that will not crawl long distances from their food source and use part of their mouth to hook on food sources.
Once the maggots enter the pupal stage, they will appear larger and their skin will turn darker (yellow, red, brown to black) and at this stage they are no longer cylindrical in the same shape as when they were in the larval stage. During the pupal stage, the fly begins to develop wings, legs, and other body parts of the adult fly in just 3 – 5 days.
When the pupa (cocoon) process is complete and they have grown into adult flies, they then fly off and look for a place to eat, eventually finding a new place to lay their eggs and starting the process again.
Such is the life cycle of flies, they reproduce quickly because they live close to food sources. Which is where they lay their eggs too. You can contact a fly extermination service if you feel the flies are very annoying.