Fruit Fly Life Cycle: Eggs, Larva & Metamorphosis

Instructor: Adrianne Baron

Adrianne has taught high school and college biology and has a master's degree in cancer biology.

Fruit flies can be an annoying pest in our lives during picnics or in our homes. However, they have a pretty fascinating life cycle. This lesson will take a look at how they progress from one stage to the next.

Fruit Fly

You are sitting at home at the table and all you want to do is enjoy a nice bowl of fruit with your morning cereal. And then it happens. You hear that all-too-familiar buzzing noise. Sure enough, there is a fruit fly flying around your head on its way to your bowl of fruit. Fruit flies are those annoying little flies that require fruit or other sugary, organic material as a food source. They need fruit throughout their entire life.

Life Cycle

The life cycle of a fruit fly includes some distinct stages: egg, larva, pupa, and adult fly. One of the amazing things about the life cycle of fruit flies is that they can go from being in the egg stage to a baby within one to two weeks. Can you imagine going from fetus to adult in less than two weeks? Let's look at how they accomplish this feat.


The first stage in the life cycle of a fruit fly is the egg stage. A female fly has the ability to lay up to 500 eggs. She starts this process by finding the perfect place, like your bowl of fruit. The fruit is even more attractive for laying eggs if the fruit is very ripe or beginning to ferment, or rot. The fermentation process causes more sugar to be available as a nutrient source for the eggs and the later stages.

The female fly will deposit her eggs inside the food to ensure the eggs are surrounded by sugar. The egg stage typically lasts for approximately 30 hours. You will not be able to see the eggs with your naked eye because they are too tiny. Under a microscope, they look like yellow grains of rice.

The eggs develop best at the temperature in which you are most comfortable in your home: between 75 and 80 degrees. The process will be slower in colder temperatures.


The second stage is the larva stage. At this point, the eggs have hatched and the fruit fly is a maggot: short, fat, little worms. Not a lot happens at the larva stage other than a whole lot of eating. The maggots will consume as much fruit or other sweet, moist foods as possible. This is important since they will need the nutrients in order to develop into the next stage.

Maggots spend their time eating as much as possible
Picture of fruit fly larvae feeding on fruit

Once they have consumed all the food they need, the maggots will move to a cool, dry, dark area to prepare for the next stage. The larva stage lasts for about three to four days. The maggots will grow a thicker, harder skin over them and move into the next stage.


The pupa stage marks the beginning of the fruit fly metamorphosis, or change in form from earlier stages to becoming an adult. The pupa is surrounded by a puparium, which is a firm, pupal case. During this stage, the pupa is completely dependent on the food and nutrients that it consumed during the larva stage.

Inside the puparium, the pupa is developing three pairs of legs and a set of wings. Over the six days of this stage, it is also getting bigger. Towards the end of the six days, the eyes turn red. You can tell when a pupa is about to emerge as a fly because the pupa will be dark in color.


If everything goes well during the pupa stage, then it will make it to the last stage, the adult fly. At this point metamorphosis is complete and the fly pushes its way out of the front portion of the puparium. The fly immediately starts eating as it depleted all of its nutrients during the pupa stage.

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