I’m not sure which insect disgusts me more, the mosquito or housefly. On one hand, mosquitoes are atrocious looking insects responsible for thousands of deaths. On the other hand, flies are repulsive creatures that spread as many as 65 diseases.

After much contemplating, I concluded that houseflies are probably the more disgusting ones because they like partying on human excrement. So while they can be useful in helping to get rid of garbage and feces, the thought of having them go from the latter to our food just barfs me out.

So I am totally confused why the heck I end up taking a lot of pictures of houseflies. I mean, it not like I enjoy doing it. Looking at them through a Macro Lens just magnifies their hideous appearances.

I’d just like to make it clear – I do not seek out these creatures. All right, maybe I did. Once. And that was just for the article entitled “The Good, the Bad, and the Ugly Insects.” After that experience, I didn’t want to go through it again.

The problem is that while I would love to photograph Praying Mantises and Dragonflies all day, there just aren’t many of them around anymore. By contrast, flies are readily available. And unlike Dragonflies, they stay still long enough for me to fiddle around with my camera’s settings before taking a picture.

So it is with my deepest apologies that I begin this article on flies. I might as well get it out of my system or their images will continue to haunt me.

[Warning: This article is about to get even uglier.]

Brief Background

Whenever someone mentions the word “fly”, the image recalled will most likely be that of the Housefly. Interestingly, the term fly refers to any two-winged insect of the order Diptera. Given this, my runner up for disgusting insects, the mosquito, also falls under this group because of its paired wings.

Houseflies can carry as many as 65 diseases, such as anthrax, dysentery, cholera, leprosy, salmonella, tuberculosis, and typhoid fever. And it is estimated that they have been passing on these pathogens for millions of years.

What may surprise few is that some scientific communities may consider houseflies to be beneficial to the planet. This is because flies, as maggots, are able to break down feces, garbage, and decomposing matter at a fast rate. Then excrement of these houseflies act as food for other forms of life, such as fungi.

Life Cycle

Similar to other insects, like butterflies, houseflies go through four stages. And unlike mammals, each stage in a housefly’s life doesn’t resemble the other.

One of the more surprising things about houseflies is that they can go from eggs to adults in just ten days! With such a short span of time, it is possible for a first batch to lay their own eggs on garbage or decomposing matter. And if the food source doesn’t dry out or get consumed, batch after batch can keep coming until the food is gone.


Each egg starts off with a pair of naughty flies mating. And while that may sound totally scientific and devoid of any moral implications, a pair of houseflies doing the deed on one’s vehicle can be rather icky.

This was the initial reaction I had when I stumbled upon a pair of naughty flies doing the dirty deed on a vehicle.

I don’t know about you, but my normal reaction would be to swat them with the nearest newspaper. I mean, it saves me the trouble of having to hunt down two separate ones. And since I had my dSLR and tripod with me instead of a paper, I ended up taking pictures of them.

[I’m so ashamed.]

Judging from the pictures I took, the only thing that would probably love a disgusting looking fly is another disgusting looking fly.


Just in case you are wondering about the differences between males and females, the egg bearing ones will be slightly larger. This is due to the fact that their bodies need to be large enough to carry several eggs, which can be as much as a 150 being laid in a period of three days.


Also known as a Maggots, they are eating machines that dine on feces, garbage, and dead plants and animals.

While full grown flies also dine on the same sources, they are nowhere near as voracious or efficient as these little wriggling things.

By the way, just in case you get any ideas about harvesting a batch of maggots from your nearest dumpster to help your wounds heal faster, stop. Houseflies are not the ones used for medical purposes.

The maggots you want come from a different species known as the Blowfly. Looking like houseflies, sterilized blowflies were used back in World War Two to clean out infected wounds of soldiers. Largely forgotten in the late twentieth century, they are slowly making a comeback due to the efficient way they remove dead and infected tissue from the healthy ones in patients.

Please note that the operative word here is “sterile.” If the Blowfly is not sterilized, it can deposit its eggs in the wounds of patients and hatch inside the body.

[Blech again.]


The Larva creates a hard casing around itself while it transforms into a winged creature. Much like the Chrysalis of a Butterfly or the Cocoon of a Moth, the pupa is composed of a hard shell to protect the fly as it undergoes the process of metamorphosis. Taking between three to five days, a full grown adult is the result of this stage.

Most maggots will bury themselves inside their food mounds before turning in to a Pupa. This is done primarily out of safety. The secondary reason is that if the food source still exists, the adult Housefly will never have to hunt for another source of nutrients.

[Blech some more.]


Complete with large compound eyes and a pair of wings, they can live as long as three months in this form.

Unlike their larval form, adult Houseflies do not have hook-like mouth parts. Instead of tearing off small chunks of food, houseflies spit digestive juices on their food then suck it back up like a straw.

With such mouth parts, it is no wonder that houseflies are attracted to material that is mostly full of liquid. In fact, the wetter the food is, the happier a fly will be.

Finally, adult houseflies are solitary in nature. The only time they get together is to mate or when many detect a source of food.

[Blech even more.]

More Useless Information I need to get off my Chest

For such a small insect, flies have quite an arsenal of equipment it uses to feed. In fact, some are so interesting that science has taken a closer look at flies to see if these things can be replicated.


Houseflies, like Dragonflies, have compound eyes. These are basically tiny fixed eyes packed into a large group to resemble a single eye. The compound eye of a housefly can number as high as 6,000.

One of the benefits of a compound eye is its field of vision. Unlike a typical mammalian eye, compound cannot be redirected. However, this fixed design points each of these tiny individual eyes in slightly different directions so creatures can see through them at all times.

The benefits of using compound eyes include the ability to detect fast movements and even to see polarized light.

In terms of technology, the idea behind compound eyes can said to have been applied to dSLR camera sensors. Using thousands of tiny lenses to capture individually capture different parts of an image, the camera’s electronic systems assemble these tiny images in to one huge one we can see on computer screens.


One of the things that affects the life of a fly is the temperature of its environment, and the warmer it is, the better it is for flies.

Warm air means that houseflies are more active. Speaking of which, you may notice an interesting phenomenon during the cold months of the year when houseflies can be seen flying at a certain height during your morning jog. They stay at this height because warmer air rises and the temperature up there is slightly higher.

As the sun goes up, dragging the temperature with it, houseflies begin to hover lower and lower till the ground temperature become comfortable for them.


Ancestors of flies actually had two pairs of wings, or two on each side. However, over the millions of years it has existed, the second pair shrunk down to what are known as Halters. Their main function is to provide balance and stability during flight.

Remove one Halter and the insect ends up flying in circles. Remove both and the fly becomes permanently grounded.

Incidentally, their wings can beat as fast as 300 times per second. And it is this high speed that helps make swatting a fly very difficult to accomplish.

The good news is that some high speed films of flies have pointed out a weakness in their flight patterns. Instead of going forward or straight up, houseflies push backwards before changing direction.

So if this study is accurate, then the best way to swat a housefly is to aim right behind it. That way, when it takes off, it will be exactly where you want it to be, which is right under your fly swatter.

Final Thoughts

You know, for someone who hates houseflies, I am surprised at how large this essay got. Starting with a few pictures and a bit or research, what was supposed to be a two-pager ballooned into five.

I guess there was so much information I just had to get off my chest. I know feel like a great burden has been lifted off my chest and hope I can finally get some sleep tonight.

[If I can only get rid of that pesky mosquito...]

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