Why fruit flies are so hard to kill

Why fruit flies are so hard to kill
  • Come summertime, fruit flies arrive in droves. They're drawn in by the smell of fruit - and by the fungi and other microorganisms that produce rot.
  • The standard fruit fly, or Drosophila melanogaster, can smell food from more than a kilometer away, and there's little that can stop them from entering your home.
  • A single female fruit fly can lay up to 100 eggs a day, which hatch into maggots in less than 24 hours.
  • To get rid of flies, experts suggest making a trap. But they'll keep coming back if you don't clean your home regularly.
  • Visit Business Insider's homepage for more stories.

Following is a transcript of the video.


Narrator: It's like they have magical powers. When the weather warms, fruit flies just appear. Out of nowhere. Next to the fruit bowl, near the trash, everywhere. And once they arrive, they are determined to stay no matter how many you swat, squash, or seize. Now as far as we know, fruit flies can't teleport into our homes from another grosser dimension. So where do they come from, and why are they so hard to get rid of?

Meet Drosophila melanogaster: your standard fruit fly. It can smell a meal from more than a kilometer away all thanks to the tiny antennae on top of its head. These antennae are specially attuned to sniff out chemicals like acetic acid let off by rotting fruit, and once they're locked on to the scent, it's nearly impossible to keep them out of your home. That's because fruit flies are about the size of a sesame seed, so they can slip through almost any crack, screen, or gap. But contrary to popular belief, it's not just the smelly fruit they're after. They're also hunting for the source of that rotting stench, specifically, fungi and other microorganisms. Yum!

And once they land for the feast, things turn even nastier. You know how you never see just one fruit fly? That's because they have incredibly fast life cycles. A single female fruit fly can lay up to 100 eggs a day, which hatch in less than 24 hours. The maggots then tunnel under the fruit skin, feeding on the microbial rot. In just a few days later, they pupate into fully fledged fruit flies. By the time day 11 or 12 rolls around, they're ready to have little maggots of their own. Aww. That's why your home can go from fruit-fly free to infested in under two weeks.

Now, by this point you might start swatting them down one by one. But it's not so easy, right? Perhaps even...fruitless? Well, scientists have discovered why. Turns out fruit flies are mathematical wizards of escape. For starters, they have around 270-degree vision, so they can see you coming from almost any angle: front, back, or side to side, and they will actually calculate the angle of your attack and plan their escape accordingly all in as little as 100 milliseconds. Scientists figured this out because of how a resting fruit fly will reposition its legs when it senses an attack. If your hand's coming from the front, for example, fruit flies move their middle legs forward, lean back, and raise their legs, allowing for a fast backwards takeoff.


Once in midair, killing them isn't much easier. They can change directions within one one-hundredth of a second and quickly accelerate by flapping their wings 200 times per second. Not bad for a brain that's even smaller than a house fly's. So then, how do you get rid of them? Some experts suggest making a trap. Fill a container with 2 centimeters of cider vinegar, cap it with a funnel, and then tape around the perimeter so that no flies can crawl out. You see, fruit flies are smart enough to find fruit but not the hole they entered.

But here's the thing. Even if you trap every last fly, they will come back as long as there's something to eat. And unfortunately for you, fruit flies aren't picky. They love rotten fruit, sure, but wine and other fermented liquids, which are chock-full of those microbes they adore, are also tasty, as is the slime that builds up in your kitchen sink. So really, the only thing you can do to get rid of them is to, well, clean up.