30 Facts about House Flies you wont Believe!

In this article, we’ll share 30 incredible facts about the common house fly!

You’ll never have thought there were so many things unique to this admittedly annoying house pest.

So sit back, grab some popcorn and learn 30 amazing facts about house flies….


The Housefly (Musca domestica, of the suborder Cyclorrhapha) evolved in the tropical climate of the Middle East and Central Asia in the Cenozoic Era, about 65-70 million years ago. Every one of us likely knows what a housefly looks like:

Please note that all the facts in this article pertain to this specific species, and not any other types of flies. The facts are organized loosely under the following headings:

  1. Two Species Related Facts;
  2. Eight Life Cycle Related Facts;
  3. Twelve Anatomical Facts;
  4. Three Facts Regarding Food Habits;
  5. Three Ways Flies Benefit the Ecosystem; and
  6. Two Oddball Facts

Read on!


The following facts all related to the common housefly species.

House Flies Live Almost Everywhere Where There Are People

Houseflies were born in Asia, most likely, but they then spread all over the world in a commensal relationship with humans – that means that flies and humans have a symbiotic relationship (yes, really!) as with all large hosts (us) and small parasites (houseflies).

As humans throughout history traveled to new destinations by multiple means of locomotion, house flies traveled with them. To complete the picture, you do not find the common housefly in wilderness habitats without humans.

If we disappeared due to a nuclear holocaust, the houseflies would likely cease to exist – unlike roaches who may hang around.

House Flies are Relatively Young Insects on this Earth

While the Cenozoic Era may look ancient the context of the human species, the housefly is not that old among insects. Flies as a whole appeared on Earth almost 250 million years ago – during the Permian period, but houseflies are a much younger species.

Interestingly enough, they appeared just before the Cretaceous period, which is when the infamous meteor strike reputed to have wiped out the dinosaurs would have occurred.


The following facts all related to the life span and activities of the common housefly.

House Flies Can Live for 15 to 30 Days, Sometimes Twice as Long

While this may not seem like an amazing fact, it does debunk a very common perception that flies only live for a day. That is not the case. There are flies that live for 24 hours – such as mayflies. But common houseflies can easily live for 15 to 30 days. Some have been known to live for as long as 60 days in certain cases.  

Houseflies are Active During the Day (and Rest at Night)

Unlike a number of other pests (like many mosquitoes and types of bugs), which may flit around after dark, the housefly’s activities are very tied to human activity. As a result, they are active during the day, when humans are awake, and rest/sleep when we do.

This ties into the symbiotic relationship between us and houseflies. In order to control flies, then, you need to target them during the daytime.

Flies May Actually Choose Their “Bed”

Research suggests that flies may actually have a favorite resting spot, typically close to their food spot, where they rest at night.

Female Houseflies Typically Mate Only Once During Their Lives

This may sound odd, but an adult female housefly will typically mate only once during their life. After mating, she will lay between 350 to 2000 eggs, in batches over a period of several days.

Males, on the Other Hand ….

The adult male housefly is super horny and will typically mate with many females over its lifetime. There is a definite “courtship” period where the male housefly looks for Ms. Right. Turns out that their ideal target is a large-sized 7-day old female, in the prime of her life.

There are some hits and misses – males have been known to target other males before going “oops!”

The Reproductive Cycle of Houseflies is Super-Efficient

As described above, female houseflies lay eggs in several rounds. Each time, she lays between 75 to 100 eggs at a go, usually on nutrient rich (for them) surfaces such as animal manure, human excrement or decaying matter.

The larva (which become maggots) hatch out within 12 to 24 hours. They transform into adult flies within 4 to 13 days in normal subtropical temperatures but could take over twice as long in cooler climates.

As mentioned above, a female housefly will, on an average, lay 500-800 eggs in her life. That’s a lot of houseflies being added to the mix – which is why it is important to eliminate nutrient rich environments around the home where flies can successfully lay eggs that hatch out.

Maggot Infestations?

One horrible fact about any fly is that their propensity for laying eggs at the nearest convenient spot may lead them to do so on humans. If an incapacitated person has an open wound, for example, or if someone has extremely poor hygiene, it is possible for flies to lay eggs within their skin.

In the rare case that it happens, maggots will feed on flesh and blood before bursting through as they mature into adult flies. This happens more often with botflies and screw flies, but it’s not impossible for houseflies to do the same.

Flies Have Acted as Aides to Detectives

The first known use of fly infestations as clues in a criminal investigation was in 13th century China. In general, studying the fly population and their larval stages at a crime scene can give forensic scientists definitive clues that help them estimate time of death and/or other events that may involve organic matter that has been spilled or burst open.


The following facts all related to the anatomy of the common housefly.

Flies Have Amazing Compound Eyes …

A pair of large complex eyes form the major part of the housefly’s head. There are some 3,000 to 6,000 simple eyes within each eye. Their eyes provide an entire panorama of what is going on to the right, left, above, and in front of the flying insect.

Flies cannot focus on specific details, unlike vertebrates – their eyes are programmed to detect anomalies in their surroundings, including movement. In other words, they are sensing threats and opportunities.

There are literally thousands of monitors alerting them to the slightest disturbance – think about this the next time a housefly eludes a swipe from your swatter.

… And Three Simple Eyes

In addition to the complex eyes, flies have three ocelli, which are simple eyes located in the middle of their foreheads. These are meant to help them navigate – like a compass – letting them know which way is up.

Since houseflies are diurnal, they gravitate towards sunlit areas. This is why you find them buzzing around windows during the daytime.

The Eyes Don’t Move, but Flies can See Behind Them

Unlike us, the eyes of flies do not move but they are able to see close to 3600, including behind them, using the thousands of tiny lenses (ommatidia) within their eyes. This allows them to navigate approaching danger.

A Functioning Set of Wings Makes the Fly Navigate like an Attack Helicopter

A fly at the top of its game (pun intended) can flap its primary wings 200 to 300 times a second and reach speeds up to 5 miles (8 kilometers) per hour. They fly with power and precision, as you’ve probably noticed – instant liftoff and precision zigzags, spirals and even back pedaling.

This maneuverability is one of the reasons why flies are hard to keep out, they can enter your house through the slightest opening.

Houseflies are Champion Fliers

Houseflies can travel a distance of up to 300 times their own length in one second. If that doesn’t sound impressive, consider this … a jetliner traveling at the speed of sound can only travel 100 times its own length in a second.

While everything is relative and proportionate to size and weight, it’s still an impressive feat of strength, agility and endurance by the housefly.

Houseflies have Amazing Reaction Times

There are several reasons why it’s really difficult to swat a fly, including their 3600 vision and agility. Another factor is their amazing reaction times.

Houseflies are able to process what they see and react extraordinarily fast – their brains process around 250 images a second. By contrast, humans can only process up to 60 images a second.

Houseflies Have Amazing, Hairy Legs

We’re not kidding. It’s actually the tiny hairs on the end of the leg segment (tarsi) that have amazing powers – of taste! Flies use their legs to taste everything they land on … this is why you may have seen houseflies walking around in circles on the surface of a potential meal.

This is not unheard of in the animal world, butterflies have the same capability.

Flies Have a Serious Sweet … Foot?

The feet of a housefly are 10 million times more sensitive to sugar than a human tongue.

Flies Have a Killer Grip and Can Walk Upside Down

The bottom part of the fly’s tarsi has tiny, gripping claws and moist suction pads (called pulvilli) which produce a glue-like substance made of sugars and oils.

Completing the helicopter illusion, flies can stick a landing on practically any surface – these pads allow flies to scale any surface, horizontal or vertical, and in fact walk upside down.

Flies Have a Very Strong Sense of Smell

Flies have an excellent sense of smell, which is how they often detect and arrive at food sources. Research has revealed that under favorable conditions, flies have been able to smell rotting flesh as much as 7 km away.

While that may be unusual, what it shows is that flies have a sense of smell which is far superior to our own.

Houseflies poop … a LOT!

Houseflies poop, on an average, every couple of minutes. This is also a major contributor to the spread of disease – they spread bacteria as well as infectious organisms as described above.

Flies Have No Teeth

Flies have no teeth. They eat by slurping fluids through a trunk-like nose or proboscis.

As depicted above, the end portion of the proboscis, called the labellum, ends in a spongy mouth which the fly uses to slurp its food. Two small feelers atop the mouth, called maxillary palps, allows the fly to taste its food.


The following facts all related to the feeding habits of the common housefly.

Flies Have a Terrible Diet (from Our Viewpoint, though it Works for Them)

While most of us are generally aware of why we should beware of flies close to our food, it still behooves us to understand what the average fly’s diet consists of – besides our food if they can get at it.

Houseflies have been called the undisputed leaders among insect-scavengers – their principal diet consists of garbage, feces and decomposing material (especially rotten flesh).

This is why flies are dangerous to humans – they carry millions of microorganisms that can cause deadly diseases such as typhoid, tuberculosis, salmonella, leprosy, cholera and dysentery, as well as conditions such as intestinal worms. Some studies posit that there are close to 100 diseases that can be borne by the common housefly.

So …. House Flies Live on A Liquid Diet

Given the lack of teeth, as described above, houseflies can only feed on liquids. They are able to turn a solid into a liquid by spitting or vomiting on it. This is one of the reasons that you should avoid eating foods that flies have sat on.

Not only do they carry germs from unsavory places (such as feces heaps) on their legs, there is a good chance that if you eat food after a fly has visited, you will be consuming its spit or vomit along with the rest of your meal. Refer to their diet above, it should be very clear why fly vomit is not something you should ingest.

Missing One Inner Wing Would Cause Them to Fly Around in Circles

A housefly’s wings are amazingly delicate instruments. Though flies appear to have only one set of wings (see below) …

… In actuality, they have tiny secondary wings as well, called halters, below the main pair. Millions of years ago, both pairs of wings were used, but they are now shrunken appendages.

However, halters are by no means useless – the fly uses them to balance in the air, by flapping them at high speed during flight. If one of the halters gets damaged or detached, the insect will be seen flying around in circles. If both halters are missing, flying would become impossible.

In addition to the inner wings, the outer wings are also delicate instruments. The smallest bit of food or debris on the wing can throw the fly off balance – which is why they often clean them.


Despite all the horrendous press flies get – and rightfully so – houseflies and their brethren species help the planet in a number of ways, which may amaze you:

Flies are Efficient Cleaning Agents

Flies recycle food wasted by us. Without them, the world would be a much dirtier place.

They Aid Decomposition of Organic Material

Flies aid the decomposition of carcasses and other rotting matter. Such actions then add to composting and enriching the soil out of which fresh life grows.

Many Species Would Become Extinct Without Flies

A number of species, such as frogs, lizards, spiders, bats, dragonflies, fish and birds have flies in their regular diet. While the housefly may not be accessible to all of them, it is certainly true that the extinction of the housefly would cause a major disruption in the food chain.


Do Flies Have Emotions? Do They Show Fear?

Scientists have experimented with various stimuli to check if flies have extended memories about unpleasant memories, and if they can exhibit learned behavior.

While the results were not conclusive, there seems to be strong indications that flies can react to a fear inducing stimulus (like a fake aerial predator casting an overhead shadow), jumping or freezing in a state of elevated arousal. Increasing the stimulus caused their responses to elevate.

Even food was ignored till the stimuli abated and their state of arousal returned to normal. The following Current Biology article lists some findings along these lines for Drosophila, or fruit flies, a species related closely to houseflies:

Houseflies … and Music?

Research has been ongoing on whether flies can react to music. Some species can definitely relate, since scientists have shown that their mating rituals involve a certain scale being produced by their rapidly flapping wings.

While not linked to that particular species, houseflies show some musical capability of their own – they always flap their wings at a pitch along the F Major scale.


We hope that the discussion above has helped you realize that even the common housefly, which is certainly and mostly a villain in our daily existence, is a wonder of nature in terms of how it has evolved and the various things that it is capable of doing.

While many of its attributes likely evoke shudders, the housefly is also capable of feats that would make it surpass the best efforts of Olympic athletes or supersonic jetliners … and for that, it deserves a brief tip of the cap, shortly before you focus on how to rid yourself of an infestation.

Having said that, here’s a totally scary look (sorry!), just in case you had become a fan …

If you want to learn more about various insects, then checkout our site categories, we have a bunch of articles there that are totally worth reading:



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All the best



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 https://schoolofbugs.com/about-steve-foster/

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