Is It Safe to Eat Food When a Fly Has Landed on It?

If a fly lands on your food for more than a second you’re going to want to throw that food away. Flies can carry hundreds of diseases like bacteria, viruses, and parasite eggs.

They also eat by spitting and throwing up on their food. The longer a fly has been on your food, the more likely it is that the fly has left germs.

Flies may also poop or even lay eggs on your food. Flies spend a lot of time in garbage and feces, and they’ll carry some of this with them and onto your food.

  • Throw away your food if a fly lands on it
  • Flies carry disease
  • Flies may poop, vomit, or lay eggs on your food
  • Food that flies have been on for a while is no longer safe to eat
  • You are, however, unlikely to become seriously ill because a fly landed on your food


How do they eat?

The eating process of flies can be slightly horrifying. Flies don’t have any teeth, so once they find something they want to eat, they regurgitate saliva onto the food surface.

This helps break the food down, so it can easily be sucked up and swallowed.

This vomit is also full of pathogens from its last meal. Germs inside flies live longer than the ones they can carry on their feet, so these diseases are more likely to cause illness.

Other bodily functions

Flies defecate frequently as well, so if they have enough time to explore your food, it is likely they have pooped somewhere on it.

It is also possible for a female fly to have laid eggs after landing on your food and staying for a while.

The places they stay

As said by food hygiene expert, Dr. Cameron Webb, it isn’t necessarily the flies but where they come from that matters.

Flies spend a large amount of time in plant and animal waste, and these areas are the home to the greatest number of pathogens and diseases. 

Flies can carry hundreds of diseases on their bodies and the little hairs on their legs, and the more they walk around on your food, the more germs they are leaving behind.

You never know where a fly just came from, another fresh sandwich, or a pile of trash.

What germs could flies carry?

Diseases specialist Brent W. Laartz says that flies can carry E. coli, salmonella, hepatitis A, and rotavirus, all serious diseases.

They might also carry Shigella, which causes diarrhea, fever, and stomach pain, and is easy to catch.

However, not every fly will carry all, if any, of those diseases. Once again, it comes down to where the flies have been.

The diseases mentioned above are not found everywhere flies eat, but are generally found in animal feces or on raw meats. 

How much should I worry?

Short amounts of time

Although everything described is extremely unpleasant, you don’t need to worry too much. If a fly lands on your food and you quickly swat it away, little harm was done.

There is still a potential risk, but the amount of disease that could have been transmitted is quite small.

The fly did not have time to vomit and try to eat or to defecate, and these are what can cause greater harm. Timing is everything here, and the more time the fly has, the more problems it can cause.

Any disease that the fly might have been carrying would also be relatively harmless. Our bodies are made to fight off germs by using our immune system.

We encounter thousands of pathogens a day, from opening a doorknob to rubbing our eyes, but our bodies know how to handle them.

If you still want to be safe, you can always break off the piece of your food that the fly landed on but still keep the rest.

This gets rid of any pathogens the fly might have been carrying, but you won’t lose all of your food. This is your best option. 

Longer amounts of time

The bigger concern is if the fly has been on the food for a while. If you didn’t notice it quickly or the food was left out and the fly had free-range, then it is much safer to just throw it out.

The fly has now had plenty of time to spit up saliva and start eating away at your food. This is a fast process and not something you want to consume.

The fly has also had time to poop or even lay eggs, especially if the food was just left sitting outside.

The more time a fly has spent on your food, the more diseases there that transferred from its body to your food. You want to swat away flies as quickly as possible.

Where you are

The greatest factor in how worried you should be is where you are in the world. In the United States, or other first world countries, you are unlikely to contract serious illnesses from flies.

In third world countries though, there is a much higher chance. Developing economies tend not to have good plumbing or health care, so flies can carry much deadlier diseases from human waste.

Flies are also more likely to cause harm in the countryside than in an urban city. Surprising right? This is because pesticides are used to help keep the fly population in check.

Rural areas not only have a greater fly population, but the flies are more likely to have been around animal waste or even carcasses.


The final problem to worry about is simply the number of flies around you. If several flies are circling your picnic area, and you are unable to keep them all off the food, it is probably better not to eat it. 

The more flies that have landed on your food, the more germs they may have left behind. 

Do I need to throw the food away?

Dr. Cameron Webb explained that any pathogens left by a fly are unlikely to make the average person sick.

If you would rather be safe than sorry, then yes, you should throw the food away. But is it going to kill you if you eat the food? No.

A quick landing won’t do enough harm to affect you. Moreover, even if the fly has been there a while, the worst that could happen is you get sick for a few days.

So throw away anything that a fly has been on for a long period, or has been touched by multiple flies, but otherwise, you will most likely be perfectly fine.

You especially want to throw away any food you have in storage that you found a fly-in. This could also include overripe or rotten fruits.

These are the perfect place for flies to lay eggs, and once they hatch, maggots eat their way right out before becoming adults just a few days later.

How do I avoid getting flies in the first place?

It isn’t possible to never have a fly land on your food, especially if you’re eating outdoors, but you can decrease the chances. One great way to do this is by using insecticides.

Always cover food if you are preparing, cooking, or serving outside. Don’t leave leftovers open outdoors either.

Always cover the food so flies have no opportunity to stop by and start eating. If you’re not eating it, it needs to be covered.

You can also use screens if you enjoy keeping windows or back doors open for fresh air. These help keep bugs out, but still allow air circulation. 

Another way to keep away flies is by minimizing garbage. Keep your house clean, especially the kitchen, and wipe up any spills or crumbs left behind.

Throw out your trash regularly and make sure it is covered. You should pick up and throw out animal waste as well.


If you’d rather be safe than sorry, your best bet is to throw away at least the part of the food that a fly has landed on.

They can carry hundreds of diseases on their legs, and they may vomit or poop directly on your food. 

However, flies are everywhere, and we have probably all eaten something a fly has been on at some point in our lives.

It is unlikely that a quick landing before you swat the fly away will cause harm. The average human is built to withstand the numerous germs countered in day-to-day life.

It is very unlikely that you will become sick simply from a single fly.

However, if the fly went unnoticed, there are many flies buzzing around, or the food was left out for a long period of time, it is best to throw the food away.

The more time a fly has with food, the more destruction it has caused and pathogens it has left in its wake.

Alright, that’s it for this article, here are a few hand-selected articles that you might also find interesting reads:

Is it Safe to Eat Food after Ants Have Gotten to It?

Fly in My Cooking Pot – Here’s What To Do Next…

What do stink bugs eat? Foods You Should Avoid Keeping At Home

Steve Foster

Mad about bugs and wanting to publish as many articles as I can to help educate people about these amazing beautiful creatures! For more info check out my about page

Recent Posts