"My Favorite Museum Exhibit": Butterflies eating a piranha

"My Favorite Museum Exhibit" is a series of posts aimed at giving BoingBoing readers a chance to show off their favorite exhibits and specimens, preferably from museums that might go overlooked in the tourism pantheon. I'll be featuring posts in this series all week. Want to see them all? Check out the archive post. I'll update the full list there every morning.

You've seen a lot of good taxidermy this week, but nothing quite like this. Renee Mertz sent me this photo of a diorama at Vienna's Naturhistorisches Museum, which depicts a group of butterflies greedily feeding off the carcass of a dead piranha.

This is not a spot of whimsy, people. This kind of thing really does happen. In fact, you can watch a real-life example (with a less-threatening fish substituted in for the piranha) in a video taken in Alabama's Bankhead National Forest.

The good news: The butterflies are not really carnivorous, per se. The bad news: What they're actually doing is still pretty damn creepy.

It's called "puddling" or "mud-puddling". The basic idea works like this: Butterflies get most of their diet in the form of nectar. They're pollinators. But nectar doesn't have all the nutrients and minerals butterflies need to survive, so they have to dip their probosces into some other food sources, as well. Depending on the species of butterfly, those other sources can include: Mineral-rich water in a shallow mud puddle, animal poop, and (yes) carrion.

When butterflies puddle over a dead fish, though, they aren't biting off chunks. Instead, they're essentially licking the dead fish—going after salt and minerals that seep out of the dead animal as it decomposes. Bonus: Some butterflies also like to lick the sweat off of humans. And a few species of moth have been documented sucking blood and tears for living animals, including humans.


  1. Great.   Now I’m going to freak out this summer if one of these flesh licking demons gets too close to my son.

  2. I’ve had a butterfly licking me, and if a little strange, it’s a great way to watch one up close. The real problem is it means you’ve been sweating more than is really comfortable, and the insect is not much help.

  3. A number of years ago, I was trekking in Borneo, in extreme humidity. When I stopped, a dozen butterflies alighted on me and started licking my sweat.  It was an incredible experience.

  4. I spent a couple months in the Peruvian Amazon and mud-puddling butterflies were a common sight. In addition to mud puddles, they also visited roadkill, drying clothes (the dirtier the better), feces, urine, garbage, and (my favourite) the dead bodies of their fellow butterflies that, while mud-puddling on the road, had been run over by cars. I’ve never looked at butterflies the same way since.

  5. It’s a common sight in tropical South America. To see the most common species of butterflies (green-yellow and white in my experience) landing to lick any salty water puddle they can find before it dries.
    Like urine, from cattle, horses or humans. Just answer nature’s call and wait a minute, they will appear from nowhere just to have a lick.

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