Fly Poop: Everything You’ve Ever Wanted to Know

Written by Emmanuel Kingsley
Updated: September 27, 2023
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Did you know that there are more than 120,000 different fly species worldwide? In fact, flies are one of the most common and diverse animal groups on Earth. As omnivorous animals, flies love to prey on nectar, sap, and blood; their main predators are lizards, fish, and frogs.

Houseflies (Musca domestica) are one of the most common flies, and one will usually find them where humans are. In fact, they make up 90% of the flies in human habitats. They’re busy animals that often irritate people with their buzzing. If you’re wondering whether their beehive of activities includes pooping, this article has all the information you need.

Do Flies Poop and Pee?

Close up of a fruit fly on a piece of fruit

Flies’ stomachs digest their meals and excrete leftover wastes through their anus.

©Ant Cooper/

Although mayflies, adult butterflies, and other animals like tardigrades, jellyfish, demodex mites, flatworms, sponges, and silkworms don’t poop, flies generally poop. Their stomachs digest their meals and excrete leftover wastes through their anus.

In fact, houseflies may poop everywhere they perch, including on your bed sheets, face, walls, and food. That’s gross, and that’s why humans should be careful when they have fly infections. No one wants to go around eating another animal’s excreta—especially that of an unclean one.

However, while flies poop, they don’t pee. They produce uric acid and, unlike humans, don’t have a different system for urine production. So, all of their waste products come out as poop. It’s important to mention that flies can fart as they produce gas from their anus, especially when defecating.

Flies can also vomit and often do so on food sources. One may also find that these animals can’t chew, so they feed by sucking up liquids with their mouths. If they come across a solid food source, they turn it into liquid through regurgitated saliva to enable them suck it.

Fruit flies love fermented food and typically feed on liquids like wine, beer, etc. They also love sugary meals and fruits like bananas, tomatoes, grapes, pineapples, and peaches. Meanwhile, blow flies love to burrow and develop inside their food sources; they love animal carcasses and fresh meat.

Flies get attracted to feces and love their smell; they also eat them and take a special liking to bird poop. Excrement contains essential nutrients like protein, fats, and minerals that flies need to develop properly. Furthermore, some flies, like mosquitoes, feed on blood.

What Does Fly Poop Look Like?

Have you ever heard of flyspeck? That’s another name for a fly’s excrement. These specks are tiny dark-colored (brown or black) dots with amber or cream-colored spots. The light spots are excess saliva that accompany their excrement. Note that flies get attracted to the poop of other flies.

Since flies feed on liquid, they can digest them very quickly. So, flies, especially house flies, defecate a lot, even on their food sources. In some situations, flies may even lay their eggs on your food. So, it’s unsafe to consume food sources that a fly has landed on.

The surest way to prevent flies from pooping on your food is to get rid of them. If you notice a fly infestation in your home, the first thing to do is ensure that your home is clean. Focus on disposing your garbage properly as doing so will remove their primary food sources and major attractant. Ensure that you don’t have rotten fruits or food materials in your home too.

Another effective way to get rid of flies is by using insecticides and any other repellent of choice. You may also decide to use light and sticky traps.

There are natural methods that have also proven effective in keeping flies away. For example, some people combine herbs and flowers, vinegar and dish soap, cayenne pepper, and water to repel these insects.

To prevent fly infestation, ensure that your home is always clean and free of substances that attract them. Also, seal your doors and windows properly, use airtight containers to store your food, ensure your garbage can has a tight lid, and turn off your lights when not in use.

What Do Flies Eat and Drink?

What Do House Flies Eat - House Flies Sucking Mango Juice

Flies love to feed on organic decaying material.


There are diverse groups of flies with different feeding strategies. Flies can be omnivores, herbivores, and carnivores, as well as parasites, decomposers, and scavengers.

Generally, most fly species love to make a meal of organic decaying material from fruits, meat, vegetables, plant secretions, etc. One may also find male and female flies sucking nectar from flowers. 

Do Flies Spread Diseases?

housefly on green leaf

Flies can transmit pathogens that cause diseases.


One reason to avoid flies at all costs is that they transmit pathogens that cause numerous diseases. They spread viruses and bacteria that can contaminate your meals and cause food poisoning when they land on them. Common symptoms of food poisoning include abdominal cramps, vomiting, fever, loss of appetite, diarrhea, and nausea.

Other common diseases that flies can spread include cholera, e.coli, dysentery, typhoid fever, and tuberculosis. Flies can also cause eye infections by transferring Chlamydia trachomatis from the eyes of infected people to uninfected individuals. They may also be responsible for yaws, a contagious tropical infection that causes red skin eruptions and joint pain.

Infected female anopheles mosquitoes transmit malaria as they suck human blood. Malaria is a life-threatening disease that has affected millions of people worldwide. As of 2020, there were about 241 million malaria cases worldwide, leading to 627,000 deaths.

What is the Brown Stuff Flies Leave?

During their feeding, flies simultaneously deposit feces on their food. Adult flies exhibit an attraction to a broad spectrum of food substances. Whenever house flies perch or settle, they leave behind “fly specks,” which are small light brown or cream-colored spots composed of saliva and excrement. These fly specks serve as potent attractants for other house flies.

Flies deposit feces wherever they land. Gradually, these fecal deposits accumulate, forming clusters resembling black dots. These clusters can be discovered on windowsills, in proximity to sink drains, and around waste receptacles.

The photo featured at the top of this post is ©

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