Why do flies rub their legs together?


​

Why do flies rub their legs together?

πŸ““ The short answer

Flies rub their legs together to clean off dust, dirt, moisture, and pollen that can interfere with their senses. Staying clean helps them fly, avoid infections, an taste with their feet.

πŸ“š The long answer

You've probably spotted a fly rubbing its little legs together and wondered what that's all about.

The options run through your head (memes linked for illustrative effect):

Although it's impossible to rule out world domination, grooming is the reason why flies rub their legs together.

In fact in 2014, researchers purposefully covered flies in dust (rude) and then observed their cleaning routine. They found that a fly might spend more than 20 minutes methodically removing dust from its head, wings, back, and legs.

But for an animal that spends a lot of its lifespan hanging around poop, why are they so concerned with staying clean? Let's dig into the reasons why flies groom themselves:

Reason #1: Flies are trying to maintain good flying performance

Flies fly. To fly well, they are loaded up with touch- and movement-sensitive receptors on their legs and other parts of their body (which also help them avoiding your swatting).

These receptors must be kept free of dirt, dust, pollen, and moisture in order for them to work effectively for flight. Flies use their hairy legs to clean their head, wings, and other legs. Cleaning is part of their pre-flight checklist.

Reason #2: Flies are trying to prevent illness

The bristles on their legs can also attract deadly molds and fungi. Constantly keeping their legs clean helps to maintain good health.

Reason #3: Flies are cleansing their palate

We humans like to think we're special because of our fancy opposable thumbs. But flies have something we don't: The ability to taste with their feet.

Flies walk around tasting for their favorite foods. (Fun fact: Fruit flies don't eat fruit. Instead they eat the yeast that forms on rotting fruit, which is why they tend to show up when you've let your fruit go too ripe.) Once their taste receptors have detected something tasty, they regurgitate saliva from their stomach to break it down into liquid. Without teeth, flies drink their food by sucking it up with a straw-like part of their mouth.

If their taste receptors get clogged with dust or dirt, they won't be as able to find their next meal. Cleaning their legs is essentially a fly's way of cleansing its palate.

Female flies also rely on their taste receptors to identify the best place to lay their eggs. Mom life! (P.S. Happy belated birthday to my mom! πŸŽ‚ ❀️)

---

Thanks for reading this week's newsletter! If you have any thoughts, questions, or favorite GIFs, my inbox is always open. Just hit reply to send me a note! :)
​

All my best,

​

​Sources for this week's newsletter​



🌐 Wikipedia article of the week

​Moberly–Jourdain incident​

"The Moberly–Jourdain incident ... is a claim of time travel and hauntings made by Charlotte Anne Moberly (1846–1937) and Eleanor Jourdain (1863–1924). In 1911, Moberly and Jourdain published a book entitled An Adventure [which] describes a visit they made to the Petit Trianon, a small chΓ’teau in the grounds of the Palace of Versailles, where they claimed to have seen the gardens as they had been in the late eighteenth century, as well as ghosts, including Marie Antoinette and others. Their story caused a sensation and was subject to much ridicule."


πŸ“š Did you know all affiliate revenue from book purchases is donated to charity?

Today You Should Know is an affiliate for Bookshop, an online book marketplace that supports local, independent bookstores.

I frequently update the Today You Should Know recommended reading list with my favorite fiction and nonfiction books. And I donate all affiliate proceeds to Room to Read, a leading nonprofit for children's literacy and girls' education across Asia and Africa.

It's a win-win-win: you get to read a book, small bookstores get some business, and money is donated to a great cause.
​


πŸ‘€ Catch up on other curious questions

P.S. πŸ€” Do you have a question for the newsletter? Click here to submit your question (or reply to this email!)


Refer friends, earn rewards!

Have a curious friend who'd love to learn more about the world? Share the link below and you'll receive rewards for referring people to Today You Should Know.

πŸ“§ (1) Refer just ONE person and receive a special "Five Fast Facts" edition of the newsletter.

πŸ“£ (5) Refer five people and I will shout you out in the newsletter.

πŸ“š (10) Refer 10 people and I will ship you a free, surprise book on an interesting topic.

Thanks for spreading the word!

[RH_REFLINK GOES HERE]

facebook twitter linkedin email

P.S. You have referred [RH_TOTREF GOES HERE] people so far.

πŸ’‘ Today You Should Know

Learn something new every Friday. Join 2,000+ nerds and satisfy your curiosity one question at a time with topics including science, technology, history, and more.

Read more from πŸ’‘ Today You Should Know
U.S. Capitol

Longtime readers of Today You Should Know may recognize this question – it's a repeat! I just returned from a fantastic trip seeing lovely people and climbing beautiful mountains. Not one word was written as I focused on being present. Hope you enjoy (re)learning about why the U.S. eats quarter pounders and not ... 113 grammers πŸ”. Back next week with a new curious question. πŸ‘‹ Caitlin Why doesn't the U.S. use the metric system? πŸ““ The short answer Pirates are a big reason why the United States...

man shaving himself

What does shaving cream do? This question came from a reader submission (thanks Saurav πŸ’˜!). Has a curious question stumped you lately? Feel free to submit your own question here: Submit your question πŸ““ The short answer Shaving cream is a specially designed soap that forms a dense, long-lasting foam. It lifts hairs for a smoother, closer shave, hydrates and protects your skin, and cleans away oils and debris as you go. πŸ“š The long answer Humans have been shaving for thousands of years, but the...

person putting hand outside of window

What causes the weird throbbing sound when you drive with only one window down? This question came from a reader submission (thanks Roger!). Has a curious question stumped you lately? Feel free to submit your own question here: Submit your question πŸ““ The short answer When wind blows over just one open window, it pushes air into and out of the cabin in a rhythmic pattern, which produces a super low frequency sound. It's the same principle that produces a sound when you blow across the top of a...