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15 Facts About Maggots

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Paul Ventner via Wikimedia Commons // CC BY-SA 3.0

Few things trigger revulsion like the sight of maggots writhing through rotting food or decomposing road kill. But maggots, which are the larval stage of flies and other related insects, are actually one of nature’s unsung heroes. Along with bacteria and other insects, they quickly break down dead things. Maggots provide other beneficial services as well, from helping solve crimes to healing wounds.

Of course, not all maggots perform such brilliant feats; some, for example, are pests that eat crops. But they don’t deserve the universally bad rap they’ve been given. So the next time your stomach lurches at the sight of maggots squirming, here are 15 examples to help you remember what amazing creatures they actually are.

1. THE LIFE CYCLE OF A MAGGOT IS PRETTY INTENSE.

Flies generally lay their eggs on things that will make a good food source for their offspring, so when maggot larvae hatch they can get to work feasting right away. Over several days they will eat, poop, grow, and sometimes even molt. At that point, the typically creamy colored maggots will pupate, meaning they’ll squirm off to a reasonably dry place, stop moving, and grow a dark shell.

Inside that shell, they transform from a mushy mass to a fully formed insect. In about 10 days, maggots will emerge from the pupal casing as hairy, bug-eyed flies and scamper off to mate, starting the cycle all over again.

2. THEY'RE VORACIOUS EATERS.

They have no legs, but their front ends have mouths with hooks that help them grab at decaying flesh and other delectable food items. Despite their endless appetites, however, they lack a sophisticated digestive system. So as they move through a corpse or rotten food, they secrete fluid containing digestive enzymes to help them dissolve their foul meal.

3. SOME MAGGOTS EAT OTHER MAGGOTS.

In 2013, researchers from the University of Lausanne published a study reporting that fruit fly maggots—normally vegetarians—actually have cannibalistic tendencies. Once a maggot is injured, it’s fair game for a feeding frenzy. Why would a normally vegetarian species do such a thing? Scientists don’t have clear answers yet, but their research studying maggots could help answer basic evolutionary questions about cannibalism.

4. THEY GENERATE A LOT OF HEAT.

Maggots feed in massive groups, and all those digestive juices and movement can really heat up their immediate environment. They deal with this by retreating to cooler spots when the temperature becomes uncomfortably hot. But research suggests that if you put enough maggots in a confined space and wait, eventually the temperature will rise to the point that they’ll start to die—somewhere between 104F° and 122F°.

5. MAGGOTS RESPOND TO LIGHT AND ODORS.

Maggots aren’t the most sophisticated creatures, but research shows some have the ability to smell particular aromas, as well as react to light. Fruit fly maggots can’t see distinct images, but they have eye-like photoreceptors known as Bolwig organs that help them detect brightness. More recently, researchers discovered they also have light-sensing cells along their body. Both help to protect them from too much light, which can be deadly for young fruit flies.

Meanwhile, other researchers have focused on studying maggots’ sense of smell. According to Matthew Cobb, a biologist at the University of Manchester in the UK, maggots have just 21 odor-receptor neurons, compared to 1300 in flies and millions in more complex animals like rats and people. In spite of this, maggots are still able to detect a surprising number of odors.

6. PEOPLE USED TO BELIEVE THAT MAGGOTS SPONTANEOUSLY APPEARED FROM NOTHING.

Science has come a long way since the 18th century. Then, people commonly accepted the theory of spontaneous generation—a belief that life could develop from non-living things, despite the fact that some two centuries earlier, in 1668, Italian physician Francesco Redi conducted a low-tech but effective experiment that showed otherwise. Redi demonstrated that maggots turned into flies, which laid eggs that turned into more maggots. He observed that maggots only appeared on meat that’s left uncovered, allowing flies to lay eggs that later hatched.

7. THEY CAN HELP SOLVE CRIMES.

We all know from our favorite TV shows that establishing the time of death is a fundamental part of a murder investigation. The time of colonization—as in, the moment at which flies arrive and begin feeding and laying eggs in decomposing flesh—helps forensic entomologists more accurately assess time of death.

It only takes a few minutes for some species of flies to begin arriving and laying eggs. So by noting the various species present and studying the age of the maggot offspring squirming around in a body, it’s possible to determine the minimum amount of time that’s passed since death.

8. MAGGOTS CAN ALSO SAVE LIVES.

Surprisingly, some species are quite effective at helping wounds heal and inhibiting infection. So-called maggot debridement therapy isn’t a new technology; it’s been observed for centuries that soldiers injured in battle often healed faster when their wounds were infested with maggots. Orthopedic surgeon William Baer, who had observed this himself in World War I, presented a groundbreaking study in 1929 showing that children with osteomyelitis (bone infection) and soft tissue wounds could be successfully treated with maggot therapy.

During the subsequent decade, thousands of doctors used maggot therapy. But the rise of antibiotics, coupled with challenges in obtaining medical-grade maggots grown in completely sterile conditions, saw the treatment dwindle. That’s changing, however, with the rise of antibiotic resistance and an increased prevalence of chronic diseases like diabetes that lead to non-healing wounds. Today, maggot therapy is making somewhat of a comeback.

9. MEDICAL MAGGOTS ARE AN FDA-APPROVED TREATMENT.

Maggots used in debridement therapy feed exclusively on rotting flesh. They help clear out the dead, bacteria-infested tissue of a wound so that healthy tissue can thrive and the wound can close. They leave healthy flesh alone. But there’s more to it than that. Maggots help curb inflammation by suppressing a part of the body’s immune system response.

Inhibiting the immune system might sound counterintuitive, but it turns out that maggots secrete a fluid capable of breaking down proteins that can trigger an overactive immune response. That overreaction by the immune system can lead to chronic inflammation, which in turn slows down healing and can increase the likelihood of infection.

In 2004, the U.S. Food and Drug Administration approved the use of medical maggots. They are typically placed in small, permeable packages and applied to the wound so that they can do their thing without crawling away (or into the body).

10. MORE TYPICAL USES FOR MAGGOTS INCLUDE HELP WITH COMPOSTING.

If you’ve ever waited too long to take the trash out in the middle of summer, you may have lifted up the lid and been repulsed at the sight of maggots writhing through last week’s leftovers. But they are actually excellent for creating rich, nutrient-laden compost.

Black soldier flies (rising stars of the maggot world—see below) are particularly speedy eaters. They work their way through organic food and animal waste so quickly that bacteria don’t stand a chance. This cuts down on odors produced by bacteria. So, bonus: your compost won’t smell as bad when these maggots are at work en masse.

11. THERE'S MONEY IN MAGGOTS.

From Colorado to South Africa, the maggot market is heating up—and helping to solve the problem of overfishing. Right now, the protein in most feed for commercial chickens, pork, and fish farms comes from ocean fisheries like sardines and herring, many of which are collapsing. That’s a huge problem, because other marine species depend on these tiny fish as their major food source. So instead of making commercial animal feed from fish meal, some forward-looking entrepreneurs are turning to farming maggots.

On a maggot farm, female black soldier flies lay about 500 eggs apiece [PDF]. This produces an army of hungry maggots that eat their way through mounds of food waste. And boy, do they eat fast. Once these plump maggots reach the pupa stage, they can be harvested—crushed, dried, and turned into animal feed. Besides protecting marine life, this keeps more food waste out of landfills, decreasing methane emissions and water pollution.

12. IN SARDINIA, MAGGOT-INFESTED CHEESE IS A DELICACY.

Ever enjoyed a dusting of Pecorino cheese on your pasta? On the Mediterranean island of Sardinia, a sheep cheese called casu marzu starts out in much the same way as Pecorino (a cheese made from sheep's milk). But then, three weeks into the curing process, the top crust is cut off, and the ripening aroma beckons to “cheese skipper” flies to come and lay their eggs.

A few weeks later, maggots hatch and begin working their way through the stinky cheese. And that’s where the magic—if you can call it that—happens. The maggots break it down with their digestive enzymes, making a special contribution to the cheese’s texture and flavor. And that’s when it’s ready to eat. The flavor of casu marzu has been described as something like a strong gorgonzola or Stilton. The European Union has outlawed it, but a handful of farms on the island still make it in the traditional way.

13. A SCIENTIST RECENTLY MADE A VIDEO OF HIS BOTFLY INFESTATION TO ILLUSTRATE THE INSECT'S LIFECYCLE.

In the tropics of Central and South America, Dermatobia hominis botflies frequently lay their tiny eggs on mosquitos. When a host mosquito lands on a warm human, body heat triggers the eggs to drop onto the skin. After they hatch, the itty bitty larvae worm their way deep under the skin and grow tiny spines that allow them to hang on tight. The parasites also release a painkilling agent to make their presence less noticeable. Sounds fun, doesn’t it?

It gets worse. Harvard entomologist Piotr Naskrecki got infected with botflies while leading a nature photography workshop in Belize. It wasn’t the first time, either, so he knew what to expect. As Naskrecki describes in his blog, he decided to let two of the larvae develop under his skin. He knew in a few weeks the larvae would grow to the size of a peanut, and pop out of his body to continue their transformation as pupae. You know, no big deal.

His reward was getting to photograph and film the invaders as they emerged from his skin, and document their transformation into flies. If your stomach is still feeling steady, you can watch the video here.

14. SOME MAGGOTS HAVE TAILS.

Rat-tailed maggots—how’s that for a name—are capable of surviving in very dirty water, like that found in stagnant ponds, lakes, and drainage areas. They get their name from their very long tails, which are actually a sort of tube that allows them to breathe under water. They are the larval stage of a drone fly, which is also known as the bee fly because of its resemblance to a honey bee.

The larvae’s tough outer covering may help protect them from bacteria present in the dirty water. But recently, scientists have discovered that there’s something else going on: the surface of their bodies is actually covered in nanopillars, spiny projections that make it difficult for bacteria in the water to congregate on the larvae. The researchers theorize that these may inhibit bacterial infection, which would explain why the maggots thrive in stagnant, dirty water where other species cannot.

15. A PARASITIC MAGGOT IS WREAKING HAVOC ON BIRDS IN THE GALAPAGOS.

Not all maggots feed exclusively on dead flesh. In the Galapagos Islands, the larvae of an invasive parasitic fly called Philornis downsi are threatening local bird populations. At least 16 of 20 species endemic to the Galapagos are in trouble because of the fly, including the famed Darwin’s mangrove finch. The flies can lay a couple hundred eggs in a bird nest. When the maggots hatch, they crawl up into baby birds’ orifices and suck their blood. Eventually the chicks die, and the maggots then feed on their corpses.

A team of scientists is working on eradicating P. downsi in the Galapagos by breeding masses of sterile male flies that can be released on the islands. As the sterile males mate with females, the population of flies should begin to drop.

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Big Questions
Why Can't Dogs Eat Chocolate?
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Even if you don’t have a dog, you probably know that they can’t eat chocolate; it’s one of the most well-known toxic substances for canines (and felines, for that matter). But just what is it about chocolate that is so toxic to dogs? Why can't dogs eat chocolate when we eat it all the time without incident?

It comes down to theobromine, a chemical in chocolate that humans can metabolize easily, but dogs cannot. “They just can’t break it down as fast as humans and so therefore, when they consume it, it can cause illness,” Mike Topper, president of the American Veterinary Medical Association, tells Mental Floss.

The toxic effects of this slow metabolization can range from a mild upset stomach to seizures, heart failure, and even death. If your dog does eat chocolate, they may get thirsty, have diarrhea, and become hyperactive and shaky. If things get really bad, that hyperactivity could turn into seizures, and they could develop an arrhythmia and have a heart attack.

While cats are even more sensitive to theobromine, they’re less likely to eat chocolate in the first place. They’re much more picky eaters, and some research has found that they can’t taste sweetness. Dogs, on the other hand, are much more likely to sit at your feet with those big, mournful eyes begging for a taste of whatever you're eating, including chocolate. (They've also been known to just swipe it off the counter when you’re not looking.)

If your dog gets a hold of your favorite candy bar, it’s best to get them to the vet within two hours. The theobromine is metabolized slowly, “therefore, if we can get it out of the stomach there will be less there to metabolize,” Topper says. Your vet might be able to induce vomiting and give your dog activated charcoal to block the absorption of the theobromine. Intravenous fluids can also help flush it out of your dog’s system before it becomes lethal.

The toxicity varies based on what kind of chocolate it is (milk chocolate has a lower dose of theobromine than dark chocolate, and baking chocolate has an especially concentrated dose), the size of your dog, and whether or not the dog has preexisting health problems, like kidney or heart issues. While any dog is going to get sick, a small, old, or unhealthy dog won't be able to handle the toxic effects as well as a large, young, healthy dog could. “A Great Dane who eats two Hershey’s kisses may not have the same [reaction] that a miniature Chihuahua that eats four Hershey’s kisses has,” Topper explains. The former might only get diarrhea, while the latter probably needs veterinary attention.

Even if you have a big dog, you shouldn’t just play it by ear, though. PetMD has a handy calculator to see just what risk levels your dog faces if he or she eats chocolate, based on the dog’s size and the amount eaten. But if your dog has already ingested chocolate, petMD shouldn’t be your go-to source. Call your vet's office, where they are already familiar with your dog’s size, age, and condition. They can give you the best advice on how toxic the dose might be and how urgent the situation is.

So if your dog eats chocolate, you’re better off paying a few hundred dollars at the vet to make your dog puke than waiting until it’s too late.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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Animals
7 Fun Facts for World Elephant Day
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Happy World Elephant Day! Celebrate the occasion with some facts about everyone's favorite gentle giant. 

1. ELEPHANTS CAN RECOGNIZE OTHER ELEPHANT CARCASSES.

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The University of Sussex's Karen McComb told National Geographic that elephants "become excited and agitated if they come across a dead elephant," and, in particular, will investigate skulls and tusks. McComb teamed up with researchers at the Amboseli Elephant Research Project in Kenya to study the behavior, showing wild elephants a range of objects that included skulls. They found that the elephants examined skulls—and tusks in particular—of their own kind twice as long as other skulls, and examined tusks six times as long as they did pieces of wood. They were even able to recognize elephant skulls with the tusks removed, but didn't show preference for certain elephant skulls over others, which suggests they didn't know which skulls belonged to their own relatives. "Animals that are intensely social in life may be most likely to display an interest in their dead," McComb told National Geographic. "But what goes on in their minds while they are doing this is a total mystery."

2. THEY'RE SCARED OF BEES.

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Forget about mice scaring off elephants: When farmers need to keep elephants away from their crops, they should use bees. Researchers in Kenya discovered that even the recorded sound of buzzing bees was enough to make elephants retreat—and cause them to emit low-frequency sound, inaudible to humans, that warns other elephants. "It's impossible to cover Africa in electric fences," Lucy King, author of the paper, told the Huffington Post. "The infrastructure doesn't exist in many places and it would restrict animals' movement." But something like a bee fence—hives strung on strong wires a certain distance apart that would move when elephants walked into them, disturbing the hives—"could be a better way to direct elephants away from farmers' crops," she said.

3. THEY MIGHT UNDERSTAND POINTING.

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Human adults and babies often use pointing as a way to nonverbally get a message across, but not many other animals grasp the concept. But according to a two-month study of 11 tame African elephants, these pachyderms might be able to: When presented with two identical buckets and pointed in the direction of the one containing food, elephants picked up on the cue fairly consistently: Elephants had a success rate of 67.5 percent (1-year-old humans have a success rate of 72.7 percent). But an earlier study of Asian elephants indicated that they don’t notice pointing gestures, which is a bit of a mystery.

4. ONE ELEPHANT CAN "TALK." 

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Koshik, an elephant in a South Korean zoo, developed the ability to imitate the sounds of five words he's heard from his trainer—annyeong (hello), anja (sit down), aniya (no), nuwo (lie down), and joa (good)—by sticking his trunk in his mouth. The scientists who first noticed Koshik’s ability speculate that he learned to “talk” because he was lonely.

5. THEY'RE DIGITIGRADES.

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It's Latin for "finger walking," and what it means is that elephants walk on their toes (there are five of them, as well a sixth false toe). According to the book Mammal Anatomy: An Illustrated Guidemost of the animals' weight "rests on a broad pad of elastic tissue behind the toes" which "acts as a shock absorber and prevents the skeleton from jolting too much when the animals walk. It also allows elephants to move surprisingly quietly despite their size."

6. AN ELEPHANT PREGNANCY LASTS ABOUT TWO YEARS.

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If you thought being pregnant for nine months was bad, be glad you're not an elephant, which can be pregnant for up to 680 days, according to the BBC. All that time in the oven has a benefit, though: Elephant calves are born with highly-developed brains, capable of learning their herds’ complex social structures and ready to put their trunks to use.

7. NINETY-SIX ELEPHANTS ARE KILLED IN AFRICA EVERY DAY.

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Unfortunately, elephant poaching remains a very big problem: An estimated 35,000 elephants are killed annually, their tusks sold illegally in the ivory market. Do the math, and that comes out to nearly 96 elephants every day. Find out what you can do to help elephants and stop poaching at 96Elephants.org.

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