All true flies belong to the Diptera order.
The name of this order means “two wings” which makes a lot of sense considering how
true flies have evolved.
Flies are just about the only insects that have a single pair of wings; most other insects
possess two pairs.
Over time, fly ancestors developed a strong, front set of wings while the back set became
a club-like structure which no longer functioned as wings.
Today we called these club-like structures halteres, and they may aid in fly aerodynamics.
Usually, when looking at common names of flies, true fly names are formed by two words such
as bot flies, house flies, and deer flies; animals that have fly in their name but are
not true flies are usually named with single words such as dragonflies, butterflies, and
stoneflies.
Of course, trying to remember all the true flies would be pretty difficult as they are
one of the largest orders of insects, and there are guessed to be more than 100,000
kinds of flies all over the world.
Insects from the Diptera order can be found on every continent in the world including
Antarctica - though their numbers there are limited to three species of which only two
are naturally occurring and all of whom are found in the warmest parts of the land - near
the ocean.
While some species of flies are found in places we would expect such as forests, wetlands,
jungles, and even our own homes, others live in extreme environments like hot springs at
112 degrees fahrenheit (44*C) (Ephydra brucei) or crude oil pools (Helaeomyia petrolei).
Plus, when thinking about flies many of us may only consider the adult form, but, in
truth, flies undergo complete metamorphosis with their egg, larval, and pupal stages potentially
(and even typically) living in habitats separate from their adult forms.
Fly eggs are laid by adults in most species (though some are not laid as eggs and develop
to later stages within the female fly).
Depending on the species, the female will lay anywhere from 1 to 100 or more eggs.
These may be placed into the flesh of a mammal, dung, soil, flowers, or even onto other flies.
After a development period of about a day the larva emerge and thus begins the great
eating frenzy.
Most flies consume the largest portions of their diet when in the larval stage with some
adult forms eating nothing at all.
All flies in the larval stage lack legs, and they will eat just about anything.
Plant matter, organic matter, feces, flesh, and garbage are all on the menu.
In fact, it’s this stage of the fly life cycle on which we have depended for the cleaning
of wounds.
After about a month has passed the fly will enter its third stage of metamorphosis as
a pupa where it develops a hard outer shell.
About one week later the adult fly emerges who may live barely more than a week to well
over a few months.
Of course, these times all vary depending on the species, but that at least gives you
an idea of the fly life cycle.
It should be noted here that mosquitos, believe it or not, are actually flies and thus it
can be said that the order of flies have caused some pretty major mishaps in human history.
The aforementioned mosquito is a vector for malaria (or basically acts as a means of transmission
of the disease), and even common house flies can be dangerous because they’ll just as
soon land on some bacteria covered garbage as they will your face.
To be fair, though, flies can also be beneficial.
Some midge flies are the sole reason we have chocolate as they seem to be the only pollinators
of cacao trees (from which chocolate is produced).
They also help in our gardens by consuming pests of our plants.
And even what some might consider the most annoying, the mosquito, is part of a food
web that ensures many fish have enough to eat.
Love flies or hate them, they do play an important role in our environment.
Most people likely associate flies with the common housefly who looks like this.
But, considering mosquitoes are also flies I’m sure you can guess the way they look
can really vary.
Some may look like this.
Or even this.
Or… this…
I guess.
Plus, they come in a vast array of colors.
What it boils down to is that they must have two wings and halteres present.
Some of the smallest can be 1mm in length while others can reach more than 7cm.
Some people believe that flies are a menace, others think that they’re a symbol of prosperity
through hard work, still more just find them annoying, and, heck, the ancient Egyptians
bestowed pendants in their shape to represent bravery.
So what do you think when you see a fly?
For more facts on flies be sure to check out the links in the description.
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