This website is reader-supported. When you buy through links on our site, we may earn a small affiliate commission.

What Is the Lifespan of a Fly?

Last Updated: 05.02.23


During the warmer season, you need to get the best fly killer to win the war against flies. Contrary to popular belief, flies don’t live for 24 or 72 hours. Depending on the species, environmental temperature, and food availability some flies could live up to 3 years. 


House flies’ lifespan

You can’t accurately predict how much a house fly will live since some of them live for 21 days and other flies can live up to 115 days. No matter how much a house flies lives, they all go through the 3 stages: larva, pupa, and adult.


Where do they come from?

If a fly lives for several weeks, it makes you wonder how there seem to be so many flies in your house. Even though house flies don’t live a long life, they are prolific breeders. A female usually lays between 75 and 120 eggs in each batch and it will lay 5 or 6 batches of eggs during her short lifespan.



Laying eggs

After mating, the male and the female fly don’t stick together. Furthermore, the female will not care for or protect the eggs. It will lay the eggs in a place where the larvae will easily find food when they emerge from the eggs. For example, it could choose to lay the eggs in animal feces, rotten food, or any other organic matter that is in the process of decay. 

From those eggs will hatch the larvae (you might know them as maggots). Depending on the temperature, the process will take between 8 and 24 hours. If there is a warm summer, it takes 7 to 10 days for a fertilized egg to become an adult. 



The larvae grow quickly. In just 2 days, they double their body size and are now ready to molt. Molting is a process through which a developing insect sheds its old exoskeleton and grows a new one. Fly larvae molt three times before they become adults, getting bigger and more developed every time.



After the third molt, the larvae will bury themselves deep into the organic matter they have been feeding on. Their skin gets darker and hardens as they enter the pupae stage. Inside its protective shell, the larva will entirely grow the body segments and appendages of the adult house fly. Usually, the pupal stage takes about 7 days. 



The adult house fly has, at most, 12 weeks to mate before it dies. But having so many natural predators, their lifespan is generally shorter. Males live for around 15 days and females for 21 days but it gives them enough them to produce approximately 900 eggs during their life.


How temperature influences the lifespan

Temperature plays a big role in the development of house flies. For example, at 99 degrees Fahrenheit a house fly will hatch from its egg in almost 8 hours. If the temperature drops to 39 degrees Fahrenheit, the same process will take 2 days.

Furthermore, in warmer days a larva needs only 4 days to become an adult. If the days are colder, it would need up to 30 days to complete the larval and pupal stage. 



How food availability influences the life span

Scientific research showed an adult house fly lives for 45 to 50 days if it has access to a moderate quantity of food. When the house flies were given unlimited supplies of food, their lifespan shortened as they lived for 30-35 days.

Scientists continued the experiment by giving different quantities of food to flies during their larval and pupal stages. House flies that received a lot of food lived longer and their reproduction capabilities increased. Both the lifespan and the reproduction capability decreased for house flies with limited access to food. 


Fruit flies’ lifespan

Just as annoying and useless as the house fly, the fruit fly has a smaller body and a shorter adult lifespan. It doesn’t take a lot of time for the fruit fly eggs to hatch. In just a day or two, the eggs will turn into larvae. 

The larval stage takes about a week. After this, the larvae will need another week to complete the pupal stage. The newly formed adult generally lives for 12 days, but some fruit flies may live for as long as 30 days. During this short life, the adult will look for a partner to mate and will lay eggs so the cycle starts over. Because they reproduce so fast, you may find a lot of fruit flies in your kitchen if you left some fruit on the counter. 

Decaying food fulfills a double role for fruit flies. They eat them and the fruit fly females will lay eggs inside them. Almost any moist, rotting or fermenting organic matter is a breeding place for the fruit fly. This includes drains, empty alcohol bottles, and garbage bins. Even though the fruit fly is not dangerous to humans, it picks up bacteria on its travels and carries it on our food.


Horse flies’ lifespan

Many people confuse them with deer flies because of their similar appearance and larval stage which occurs in the same type of environment. They even have the same lifespan as they could live between 1 and 3 years. However, the horse fly has darker colored wings and it feeds off other animals besides deer. It is not uncommon for horse flies to feed off humans.

But only the female horse fly is capable of sucking blood from animals, as male horse flies have a different mouthpiece which can’t be used to bite through skin. The female horse fly must have a blood meal before she lays the eggs. The protein provided by this meal will support egg production.


Laying eggs

Female horse flies produce between 250 and 1,000 eggs. You may think so many eggs require a lot of space but the horse fly females solve this space problem by laying the eggs in tiers. Horse fly eggs are dark-colored and are shaped like spindles. The eggs are usually laid on vegetation hanging over waters, and it takes 12 days for them to hatch.



The larval stage

The horse fly larval stage takes place in the moist ground or other types of wetlands. The horse fly has one of the longest larval stages as it can take as long as 3 years to be completed. When the eggs hatch, the larvae fall into the ground and bury themselves into the soil. 

If the eggs are laid above a lake of a pond, the larvae will fall into the water and they will be carried to dry land. The horse fly larva will feed on almost any organic matter available as it could eat other insects, earthworms or another horsefly larva. In the spring, the larval stage is completed and they enter the pupal stage.  


The pupal stage

In general, for a developing horse fly, the pupal stage takes place on dry land. It is better known as the cocoon stage. Depending on the environmental conditions and the species, this stage can last from 7 to 14 days. 


The adult stage

The adult horse fly will materialize at the end of the pupal stage. Horse flies enter the adult period during the late summer. As adults, horse flies are good fliers and will promptly look for food and a mating partner. While females will search for a blood meal, males will consume plant juices and nectar.


Cluster flies’ lifespan

If having house flies visiting you during the summer is not a great cause of worries, cluster flies could be more tricky in autumn as they usually show up in big numbers. At the beginning of the autumn, they will gather around windows as light attracts them so this is your best chance to get rid of them.

The cluster fly has a lifespan of 30 to 50 days. But the cold weather slows their activity and they manage to survive the winter if they find shelter. Even if you see only a few of them, there could be a lot more already huddled up in the warm and safe spaces of your house. 

However, cluster flies reproduce outdoors so you don’t have to worry about cluster flies hatching from your walls. They produce 3 generations of eggs each summer and the last one migrates to houses or other buildings at the end of September. It seems that buildings placed on high ground are the most tempting refuges for these migrating flies.



Leave a comment

0 Comments Protection Status