We tend to swat flies away — from our faces, our food, our houses. But what if we took a closer look instead?
Flies are so common, and often so pesty, that it’s easy to overlook how many incredible adaptations they have, and the impact they have on our planet.
Masters of flight
You can hear flies coming toward and around you. Their two wings can flap incredibly fast — 200 times every second! Try it! How many times can you flap your arms in one second? How many seconds does it take to flap your arms 200 times? You’d probably start to slow down after awhile. Flies can change their speed too.
Words to know
Acrobatic: Adept at spectacular gymnastic feats.
Decomposer: An organism that decomposes organic material.
Hygienic: Conducive to maintaining health and preventing disease.
The sound they make changes depending on how fast they flap. Slower flaps make a lower-pitched buzz. The faster they flap, the higher the pitch rises. Try to listen the next time flies buzz around you. Do they sound different from each other?
Flies also have halteres, or modified hind wings. Halteres look like sticks with a knob at the end, kind of like miniature doorknobs or walking sticks. Rather than flapping, they work by vibrating up and down to help flies stay steady. Did you know airplanes and seacrafts do the same thing with something called a gyroscope? Even on windy days flies don’t get blown off course! Halteres would sure come in handy if you were trying to balance on a tightrope!
Defying gravity
After completing acrobatic flying feats, flies stick the perfect landing, even sideways or upside down. Tiny hairs on their feet produce a sticky substance, like glue, made from sugars and oils. Sounds like an experiment you could make at home with pantry items — but ask a grownup first!
Not only can flies land upside down, right-side up or sideways at any angle, they can climb in any direction too. Where would you go if you could climb upside down?
Compound eyes and complex brains
Has anyone snuck up on you before? Probably. But good luck sneaking up on a fly. Flies can see in all directions at once! And they don’t have to turn their heads to do it. In fact, flies can’t move their eyes at all. Unlike humans, they can’t give their bestie the side eye or roll their eyes at a lame joke. Instead, they have compound eyes made up of 4,000 lenses each! For comparison, human eyes only have 2 lenses each. So house flies can keep an eye out for danger, like fly swatters or birds, while looking for their next trash-can meal, sneaking a cookie and watching for tattletales.
Not only can they see in all directions at once, their brains can process 250 images every second. Humans can only process 60 images. That’s why they’re so hard to sneak up on.
No teeth, no problem
Flies can’t chew — they have no teeth. But they land on our food. So what are they eating, and how?
What can you eat without chewing? How about a milkshake or soup? Liquid food! Some insects, like cicadas, have straw-like mouthparts to suck liquids. Flies’ mouthparts more closely resemble a sponge, absorbing the liquid they touch. Part of the appeal of a fly’s trash-can diet is that rotting food starts to ooze.
But wait! If flies can only eat liquid food, why do they land on solid food too? Flies have the ability to turn solids into liquids. No, it’s not magic. It’s regurgitation! They regurgitate, or throw up, digestive juices. Those acidic juices start to dissolve the solid food into a liquidy substance flies can sponge up. Humans have digestive juices too, but aren’t you glad you don’t have to throw up on your pizza before you can eat it?
Clean and dirty
Where do you see the most house flies? Did you think of trash cans? Or maybe dog poop? Strong smells that humans often find gross attract house flies. Because garbage and poop are dirty things, house flies get the reputation of being dirty too. But how true is that?
Do your grownups remind you to wash your hands before eating? House flies have the same habit. Tiny, bristly hairs called setae cover their bodies. Setae help with their senses, so it’s important to keep clean. Flies scrub those tiny hairs every time they land. Have you ever noticed a fly rubbing its front legs over its body like a cat grooming itself? How hygienic ... for them. For us, not so much.
Where do flies often land after visiting trash cans and poop piles? On our food or on our skin. When they scrub their setae, the bacteria that falls off has to land somewhere. But you can take measures to protect yourself by covering food that’s outside, trying to keep flies out of your home, and, like your grownups keep reminding you, wash your hands before you eat!
Positive impacts
Flies aren’t just picnic interrupters and bacteria spreaders. In fact, they work hard behind the scenes to the benefit of people and the planet. The flies and their larvae that you find on waste? They, and other decomposers, break it down. Without decomposers there would be poop and rot everywhere. Now that would be really gross!
Once the larvae complete their metamorphosis and can fly, they visit flowers, pollinating along the way. Without flies and other pollinators like butterflies, flowers could not produce seeds or fruits and humans would struggle for food sources.
All creatures big or small, cuddly or pesty, have their role to play for the success of the planet. What’s yours?
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