What Does a Fly Do When It Lands on You? The Fascinating Science Inside.

Have you ever been outdoors and felt the presence of a fly on your skin? This annoying sensation can be distracting and frustrating, but have you ever wondered what it is that a fly does when it lands on you? What is their purpose, and how do they interact with humans? For something so common, there is a surprising amount of fascinating science behind the interaction between man and fly. Let’s explore this topic and unveil the little-known mechanisms of the fly when it lands on you.

What Happens When a Fly Lands on Your Skin?

When a fly lands on your skin, it may seem like they’re just resting, but the reality is much more complex. Flies have sensitive hairs all over their bodies, including their feet, which can detect a wide range of chemicals, temperature changes, and air pressure. When they land on you, they use these hairs to identify whether you’re a suitable host for them to feed or lay eggs.

Once a fly determines that you’re a possibility for them, they will probe your skin with their proboscis, a long, slender tube-like organ used for drinking fluids. This probing usually doesn’t hurt because it isn’t designed to pierce the skin, but rather test the surface for sources of food, moisture, and organic matter.

Why Do Flies Like Landing on Humans?

Flies like landing on humans because we’re a source of food, heat, and shelter. Humans are warm-blooded, and our bodies give off heat, so we’re attractive to flies seeking a warm place to rest. Additionally, our skin secretes a variety of sweat and oils that flies find highly attractive. This combination of warmth and food makes humans an ideal target for flies.

How Do Flies Identify Humans as a Suitable Host?

Flies use their sensory organs to detect chemicals in the air, which can help them locate potential hosts. They’re drawn to carbon dioxide, ammonia, and other chemicals present in human breath and sweat. Once they’ve identified the source of these chemicals, they fly to the host and land on their skin, testing for the presence of food and moisture.

Can Flies Transmit Disease?

Flies can carry a wide range of diseases, including typhoid, cholera, and dysentery. These diseases are primarily transmitted through contact with fecal matter or contaminated food. When a fly lands on a surface, it can transfer bacteria and viruses to that surface via tiny particles of contaminated feces or regurgitated saliva.

If a fly lands on your skin, it can potentially transmit disease if it’s carrying a pathogen at that time. However, the risk of disease transmission from a fly landing on you is generally low. Flies are not a significant source of transmission of most human diseases, but precautions should still be taken to minimize contact with flies to protect yourself.

How Do Flies Feed?

Flies feed by sponging up fluids. They have a proboscis that they use to pierce through skin or other surfaces to access fluids. Once they’ve made a connection, they use their muscles to pump fluids through the proboscis and into their digestive system.

What Do Flies Eat?

Flies are opportunistic feeders and will eat almost anything they can get their proboscis on. Their diet includes decaying plant and animal matter, secretions from animals, sweat, and blood. They will even consume fecal matter, which can lead to the transmission of harmful bacteria and viruses.

Why Do Flies Regurgitate?

Flies regurgitate enzymes onto the things they eat to break them down further. Their stomachs can’t digest certain proteins and fats, so they need to break them down outside of their bodies. When they regurgitate onto food, enzymes break it down further, making it easier for the fly to consume it.

How Fast Can Flies Move?

Flies are incredibly fast movers and can fly up to 5 miles per hour, making them challenging to swat or catch. Additionally, they are agile and can fly in any direction, making it difficult to anticipate their movements.

How Can You Keep Flies Away?

There are several ways to keep flies away. One of the most effective methods is to keep your environment clean and free of organic material that attracts them. Make sure to store food properly and clean up spills and crumbs promptly to reduce food sources.

Additionally, using fly traps and insecticides can help control their population. Keeping windows and doors closed and using screens can also reduce the number of flies that enter your home or office.


Flies are an ubiquitous presence in our lives, and their interactions with us are complex and fascinating. They are attracted to us by our warmth and the chemicals we emit and probe us to determine if we’re a food source. Although they can transmit diseases, the risk of transmission is generally low.

By understanding what attracts flies and how they feed, we can take measures to keep them away from our homes and businesses, minimizing their impact on our lives.


  • What are flies attracted to?
    • Flies are attracted to warmth, food, moisture, and chemicals emitted by humans and other animals.
  • Can flies transmit disease?
    • Yes, flies can transmit diseases, including cholera, typhoid, and dysentery. They can transfer bacteria and viruses via contaminated surfaces or food.
  • How can you get rid of flies?
    • You can get rid of flies by keeping your environment clean and free of organic material, using fly traps and insecticides, and covering windows and doors with screens.
  • What do flies eat?
    • Flies eat decaying plant and animal matter, animal secretions, sweat, and even fecal matter.
  • How fast can flies move?
    • Flies can fly up to 5 miles per hour and can be highly agile in their movements.


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  • Lalander, C., et al. “Faecal Bacteria Detected by PCR Associated with Health and Disease in Wildlife-Microbial Load, Inhibition Diagnostics, and Carriage Estimation.” Journal of Applied Microbiology, vol. 121, no. 2, Aug. 2016, pp. 514–525, doi:10.1111/jam.13175.
  • Satterlee, D. G., et al. “Heartbeat Coupling to Dopamine Release in the Fly Brain in Vivo.” Proceedings of the National Academy of Sciences of the United States of America, vol. 117, no. 21, May 2020, pp. 11441–11450, doi:10.1073/pnas.1913786117.

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