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Where Do Fruit Flies Come From?

Last Updated: 05.02.23


If you read one of our recent posts you found out how to get rid of flies. But where do they come from? As we know, fruit flies seem to appear out of nowhere during the warmer seasons. Whether they get in the house through an open window, a fruit from the store, or pre-laid eggs, they always find a way inside your home.


What people thought about them

For a long time, people believed fruit flies were a result of spontaneous generations as they seemed to spawn from rotting fruit or meat. However, this theory was invalidated a few hundred years ago and we now are aware of the truth about these annoying insects.

The reality is that fruit flies (known by scientists as Drosophila melanogaster) can detect a rotting fruit from several miles away. As contrary to our old beliefs, they don’t come from inside of the rotting fruit. These stealthy little fliers come from outside of your house looking for that fruit. 



Closed windows will not stop them

If you think keeping all the windows closed will keep them away, you might want to reconsider this strategy. Fruit flies are so small they can enter your house through the tiniest crack around doors or windows. Not even a window screen will stop them as they can fly through it.


What makes them coming?

Fruit flies don’t have teeth so they look for liquid food to eat. So wine, fruit, vegetables, and almost any fermented organic matter are the main sources of food for fruit flies. So simply having these common foods in your house is like an open invitation for flies to come.

If some fruits in your kitchen are overripe or they start to go bad, the fermentation process begins. When fruit begins to ferments it produces alcohol, which will attract fruit flies. Every time you have ripe fruits in your kitchen or are enjoying a glass of wine outdoors, it doesn’t take long until these little nuisances appear. 


How do they reproduce so fast?

After they find the rotting fruit, they continue to consume it, and during the process, fruit flies lay hundreds of eggs. The juices from the fruit or organic matter are consumed by fruit flies as they ingest it through a mouthpiece.

Larvae will hatch from these eggs in mere hours. If you’ll ever happen to leave a fruit bowl on the kitchen counter for a few days, you will have an entire fly colony when you return home. It is difficult to spot the eggs with the naked eye so there is a big chance you will ingest some fly eggs when you eat fruit. The best way to reduce the risk is to thoroughly wash every piece of fruit you intend to eat.


From larvae to adult

After hatching from the eggs as gelatinous globs, they undergo a fast transformation to adult fruit flies with complete flight ability, motion, and sight. Larve will eat as many nutrients as possible and they will move to a dark spot where they can complete their evolution uninterrupted.

Outdoors, this process usually takes place in a layer of soil. If they undergo the metamorphosis inside, they will pupate in the soil of a potted plant or will look for a small crack where they are safe.


What’s the lifespan of a fruit fly?

In general, a fruit fly lives for approximately 6 weeks. After a week in the pupae stage, it becomes an adult after having grown wings and 6 legs. So they are able to search for a source of energy. And that source is your vegetables and fruits as you probably guessed. The females begin to lay new eggs into your food so the life cycle starts over again.



Fruit flies outside of the kitchen

You might be surprised to find a large number of fruit flies hovering around your bedroom or living room. You don’t keep food in these rooms. So why did they go there?

It doesn’t take a lot to make them invade every room of your house. A small stimulus such as a drink spill that wasn’t cleaned well is enough for them. They could also be attracted by a fresh flowering plant or some flowers that are just starting to fade. 


Eating fruit flies by accident

Even though most of the people don’t eat fruit flies on purpose (or at least that’s what we think), sometimes it could happen. Since fruit flies like food that started to rot, they carry around a lot of bacteria. Just like houseflies, bacteria from previous stops remain on the body of the fruit fly.

There is a small chance that a fruit fly will go straight into your mouth or even remain on a piece of fruit that you are eating. But sometimes they get stuck in your drink or food and if you don’t see them, they become part of your menu for that meal.

However, eating an insect by accident is not as unusual as you may think. It has been estimated that people will accidentally eat almost a pound of insects or insect parts over the course of their entire life.

Insects are inescapable so it’s almost impossible to eliminate them completely from our food. And we might not want to do that as most of them will not hurt us and the number of pesticides should be dramatically increased so we could be anywhere near that goal.


Are fruit flies dangerous?

First of all, fruit flies don’t bite or sting so they can’t do a lot to hurt people. Even though they carry around a lot of bacteria, they are not considered to be a disease vector.

Any organism that can transmit diseases to humans is called a disease vector. One of the most known disease vectors is the mosquito because it can transmit malaria and so are the fleas which are responsible for spreading the bubonic plague.

Most disease vectors are organisms capable of biting or interacting with your blood. But fruit flies can’t do that. So you will be satisfied to find out that fruit flies don’t pass on pathogens to humans.

Furthermore, not even babies are affected by fruit flies. They would not have any adverse reactions to the fruit flies’ presence that the parents or other relatives would not experience themselves. However, they are still gross. They lay eggs in your food, the larvae feed on the same fruit as you might want to eat, then they go around your home carrying a lot of germs. 


How to get rid of fruit flies

It is very hard to completely eradicate the fruit flies from your home. They are attracted to sugary, organic materials so almost every food will make them come back. As their name says, they have a lot of interest in fruit. Nevertheless, they can reproduce using rotten meat, trash bins or big spills of juice or alcohol.

If you want to get rid of them, you must destroy their feeding and breeding grounds. Keep in mind they generally lay the eggs in overripe fruit and other sweet, soft, organic matter. If you spot a fruit fly infestation in your house, throw away all overripe or damaged fruit. 

Also, clean the kitchen counters as there could be some organic matter for flies to feed on. Empty the trash can and spray some disinfectant to clean them completely. After getting rid of the feeding and breeding ground, you may use some of the control methods. Although they will not completely disappear in the first days, the lack of food available for them will eventually make the fly population die out.



Other methods that you could use

You can clean the infested drains by pouring down bacterial digesters. If you leave your house for a few days, you can use bleach. This is effective if it stays in the drains long enough to act on the accumulated gunk that attracts fruit flies.


Using plants and herbs

One of the best ways to keep them away is to use strongly scented plants. One of the most common options is to use basil. You can get basil from almost any store and its anti-bacterial and anti-viral properties make it beneficial for your house environment.  

If you are not a fan of basil, there are some other options for you. Lavender, bay leaf, tansy, and wormwood are great weapons in the war against flies. Put some of these scented plants around your house, preferably near a window or a door to prevent the flies from entering.



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