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Flickr user Langston Creative

10 Fun Firefly Facts

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Flickr user Langston Creative

No summer evening is complete without watching—and sometimes catching—fireflies. There are about 2000 different species of lightning bugs, and there's still a lot that scientists don't know about them. Here are a few things we do know.

1. They’re actually not flies—they’re beetles.

Courtesy of Flickr user Wesley Fleming

Up close, it's easier to see that fireflies are beetles. And like all other beetles, they have hardened forewings. Fireflies use the forewings—also called elytra—for balance while in flight.

2. A firefly's glow is a chemical reaction—which makes them bioluminescent.

According to LiveScience, the light is produced when oxygen is mixed with a pigment called luciferin, an enzyme called luciferase, and a chemical that provides cells with energy called adenosine triphosphate. The final part of the formula is uric acid crystals, which are located in the cells that make the light and shine the light away from the firefly's body. (The light-emitting part of the firefly is called a photic organ, by the way.)

3. Males focus on finding a mate.

At the nucleus of their night flights, the brightness of their glow, and their flashing patterns is one thing: reproduction. These guys are intent on mating. Typically, the females sit immobile, and only flash back when they see a male with a particularly impressive display.

4. Each species has its own flash pattern.

As males fly through the air searching for a mate, each uses a "flash fingerprint" specific to its species. According to the American Museum of Natural History,

Males fly through the air and search for females with a species-specific light display. Some flash only once. Some emit “flash trains” of up to nine carefully timed pulses. Others fly in specific aerial patterns, briefly dipping before sharply ascending and forming a “J” of light. A few even shake their abdomens from side to side and appear to be twinkling.

Scientists can use these patterns to determine how many species are in an area.

5. Some sync up.

Called "simultaneous bioluminescence" by scientists, the phenomenon of fireflies flashing in unison only happens in two places in the world: southeast Asia and the Great Smoky Mountains National Park in Tennessee.

6. Flashing fireflies almost don’t exist west of the Rocky Mountains.

There are a few rare exceptions, but for the most part, flashing fireflies don't live west of the Rockies. Why? Well, no one is really sure. Whereas flashing fireflies communicate with their flickers, non-flashing ones use phermones to stay in touch with one another.

7. They can be poisonous.

Not only do fireflies taste nasty, they can actually kill. When predators attack, fireflies kick in to a process called "reflex bleeding." They shed drops of blood that contain bitter-tasting chemicals that are poisonous to vertebrates, including lizards and sometimes birds. They're not so great for humans, either: When scientist Marc Branham with the American Museum of Natural History gently put a firefly he'd caught in a net between his lips (his hands were full with a jar), “Both lips went numb. Then my throat constricted. They really taste sort of astringent. I quickly put them into my jar and I haven’t done that since.”

8. In much of Europe, female fireflies don’t actually fly.

European female fireflies remain flightless into adulthood and take on the form of a worm that glows rather than flashes.

9. Female fireflies can be cannibalistic.

In general, fireflies don't feed, but when they do, they tend to eat mites or pollen. However, the femme fatales of the genus Photuris like the taste of their own. Using "aggressive mimicry," the female of this particular subfamily waits for a male firefly to flash, then imitates that male's flash pattern, suggesting that she is a receptive mate. After luring him in, she chows down.

10. And the larvae aren't a picnic, either.

These glowing worms will follow the slime trails of snails and slugs, paralyze them with a bite, and chow down.

Sources: National GeographicAbout, Firefly, LiveScience, and American Museum of Natural History ( target="_blank">2), Animal New York

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iStock // Ekaterina Minaeva
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Man Buys Two Metric Tons of LEGO Bricks; Sorts Them Via Machine Learning
May 21, 2017
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iStock // Ekaterina Minaeva

Jacques Mattheij made a small, but awesome, mistake. He went on eBay one evening and bid on a bunch of bulk LEGO brick auctions, then went to sleep. Upon waking, he discovered that he was the high bidder on many, and was now the proud owner of two tons of LEGO bricks. (This is about 4400 pounds.) He wrote, "[L]esson 1: if you win almost all bids you are bidding too high."

Mattheij had noticed that bulk, unsorted bricks sell for something like €10/kilogram, whereas sets are roughly €40/kg and rare parts go for up to €100/kg. Much of the value of the bricks is in their sorting. If he could reduce the entropy of these bins of unsorted bricks, he could make a tidy profit. While many people do this work by hand, the problem is enormous—just the kind of challenge for a computer. Mattheij writes:

There are 38000+ shapes and there are 100+ possible shades of color (you can roughly tell how old someone is by asking them what lego colors they remember from their youth).

In the following months, Mattheij built a proof-of-concept sorting system using, of course, LEGO. He broke the problem down into a series of sub-problems (including "feeding LEGO reliably from a hopper is surprisingly hard," one of those facts of nature that will stymie even the best system design). After tinkering with the prototype at length, he expanded the system to a surprisingly complex system of conveyer belts (powered by a home treadmill), various pieces of cabinetry, and "copious quantities of crazy glue."

Here's a video showing the current system running at low speed:

The key part of the system was running the bricks past a camera paired with a computer running a neural net-based image classifier. That allows the computer (when sufficiently trained on brick images) to recognize bricks and thus categorize them by color, shape, or other parameters. Remember that as bricks pass by, they can be in any orientation, can be dirty, can even be stuck to other pieces. So having a flexible software system is key to recognizing—in a fraction of a second—what a given brick is, in order to sort it out. When a match is found, a jet of compressed air pops the piece off the conveyer belt and into a waiting bin.

After much experimentation, Mattheij rewrote the software (several times in fact) to accomplish a variety of basic tasks. At its core, the system takes images from a webcam and feeds them to a neural network to do the classification. Of course, the neural net needs to be "trained" by showing it lots of images, and telling it what those images represent. Mattheij's breakthrough was allowing the machine to effectively train itself, with guidance: Running pieces through allows the system to take its own photos, make a guess, and build on that guess. As long as Mattheij corrects the incorrect guesses, he ends up with a decent (and self-reinforcing) corpus of training data. As the machine continues running, it can rack up more training, allowing it to recognize a broad variety of pieces on the fly.

Here's another video, focusing on how the pieces move on conveyer belts (running at slow speed so puny humans can follow). You can also see the air jets in action:

In an email interview, Mattheij told Mental Floss that the system currently sorts LEGO bricks into more than 50 categories. It can also be run in a color-sorting mode to bin the parts across 12 color groups. (Thus at present you'd likely do a two-pass sort on the bricks: once for shape, then a separate pass for color.) He continues to refine the system, with a focus on making its recognition abilities faster. At some point down the line, he plans to make the software portion open source. You're on your own as far as building conveyer belts, bins, and so forth.

Check out Mattheij's writeup in two parts for more information. It starts with an overview of the story, followed up with a deep dive on the software. He's also tweeting about the project (among other things). And if you look around a bit, you'll find bulk LEGO brick auctions online—it's definitely a thing!

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May 23, 2017
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