Males Can Sniff Out A Well Fed Female July 8, 2011
Posted by Mrs Weird Scientist in Animals, Brain Power, Insects, Think About It.Tags: black widow spider, cannibal, female, male
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If they’re a male black widow spider, that is. Simply by taking a little saunter across the female’s web, a male black widow can sense if a female is hungry or not. Why does it matter? Because female black widow spiders have a rather freaky habit of eating the male after mating. It’s how they earned their dangerous name.
Now that's one massive female black widow spider. You would almost think she's been doing some seriously heavy weights at the gym. But nope, females are normally much bigger than males. Those males best watch out!
The Smell Of Safety
Males have developed this very useful technique, which tells them whether or not a female has recently eaten. But if a female is hungry, she would be more likely to cannibalize the male spider. They take a sniff of those silk strands and then decide if they want to proceed or scurry away. A new study discovered this interesting skill and published the findings in the journal Animal Behaviour. So, how do researchers actually go about testing something like this?
Feeding Time For The Ladies
First things first. The researchers fed a bunch of hungry female back widow spiders. Using a cricket neatly held between forceps, they rested it on the web and waited for the female to come over, wrap the cricket in silk and chow down. The females got one cricket each week. Yet, by the time the fourth week came around, they weren’t so hungry anymore and didn’t really want to eat the crickets.
I bet this female black widow spider is thinking: "Ah, the satisfaction from a good meal of crickets. I think I'll accept the advances of the male spider perched nearby. Since I'm well fed, I probably won't eat him after we're done."
Another bunch of female black widow spiders were starved for a few weeks. It apparently didn’t put their lives at risk, but they did get a bit smaller. Now, let’s find out what happened when a male was placed on the web of a well fed or a starved spider.
One Step, Two Step, Three Step…Four
Since the male spiders can pick up scents with their feet, they were able to figure out the difference from one female to another just by walking on the web. Normally, a male black widow spider has a special dance he does to court the female.
In this experiment, the males danced far more actively on the webs of well fed females. Smart dudes! If anything, dancing and mating would leave them ready to eat – not be eaten! Typically, they dance around for an hour or two, which sure shows their dedication to the purpose. They wave their legs and pluck and tap at the web in a unique way, so that unlike prey they show the female they are interested to mate rather than become dinner.
If Only I Had Such Powers
Now I have a strong sense of smell but definitely nothing like these male black widow spiders. It’s too bad because I’m really scared of spiders even though I know most are harmless. If I had my way, I’d be able to simply smell any spider from several meters away. That would give my timid self enough time to run!
How To Be An Assassin February 21, 2010
Posted by Mrs Weird Scientist in Animals, Brain Power, Insects, Think About It.Tags: assassin bug, prey, spiders
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Credit: Video generously provided by Anne Wignall of Macquarie University.
Imagine you’re a hungry insect. To get your next meal, you need to be a true assassin, using stealthy tactics to capture your prey. Well if you were an assassin bug, then your plan might read like this:
1. Slowly approach your prey
2. Tap the web before each step
3. Bounce around a bit
4. Grab some web strings
5. POUNCE
It might sound like a strange plan but it works! The assassin bug does all these bizarre movements to trick the spider into thinking it has an insect caught in its web. Once the spider is sure that it has its next meal, it scurries over to the assassin bug. But too bad for the spider, it will now become a tasty meal for this sneaky insect. To find out more about this peculiar bug, I chatted with Anne Wignall of Macquarie University in Sydney, Australia, who had some of her recent work published in the Journal of Ethology. Anne already knew that some bugs would hunt down spiders but she wanted to find out just how they did it! Anne explained to me:
When I heard that there was a bug that seemed to lure spiders toward them, I was instantly fascinated because it seems like such a crazy thing to do, when spiders are such dangerous predators themselves.
In fact, there is actually one more step in the assassin bug’s plan, which could come in at number six. Once the assassin bug grabs the spider, it sometimes will tap the spider with its antennae. Researchers think this might be a way to hypnotize the spider, making it harder to escape.
A World Of Assassins
The assassin bug in the video above is a species known as Stenolemus bituberus. But if you thought it was the only one, think again! Anne describes just how busy our world really is when you get outside:
There’s also lots and lots of other assassin bug species and insects that use stalking, deception, luring and other cool tactics to hunt other invertebrates, and we’re finding more all the time.
So this means there are way more bugs out there with incredible, assassin-like tactics to capture their prey. For example, Todd Blackledge of the University of Akron in Ohio has been investigating how wasps hunt spiders. He found that adult female wasps will capture spiders and sting them. Ouch! But that isn’t all. The wasp then lays an egg on the spider, which allows the wasp larva to eat the spider, helping it grow into an adult.
Your Garden: A Battleground For Bugs
Now that you’ve checked out the video above, you might actually be able to find one of these creepy crawlies in your garden. Anne suggests that if you live along the east coast of Australia, you should explore the trees and webs in your garden, where you might find an assassin bug battling it out with a spider. Just be glad that while those hungry bugs fight it out, you don’t have to go through anything quite so dramatic when you want to have lunch. In fact, make yourself a nice sandwich, grab your camera, then see what you can find in your backyard!
The Return Of Bed Bugs – Smarter Ones January 13, 2010
Posted by Mrs Weird Scientist in Animals, Evolution, Insects, Tough Stuff.Tags: bed bugs, bites, DDT, infestation, pests
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Your mattress may be home to more than your pillow or favorite stuffed animal. It could be the home of bed bugs!
The title reads like a horror movie but for those who have battled it out with bed bugs, it makes a lot of sense. Others might think that ‘don’t let the bed bugs bite’ was just some bedtime line their parents used as a cute joke.
In fact, let’s see now who knew that bed bugs really existed. Try out the poll below (be honest!).
Bed Bug Basics
Bed bugs are small, reddish brown insects that feed on human blood, which engorges them and makes them bigger. They are from the insect family Cimicidae and common bed bugs are formally called Cimex lectularius. They tend to be most active at night, coming out of the cracks in walls or bed frames and other hiding places to get their bloody grub. They can travel in suitcases, so hotels are a hot spot for bed bugs as well as other places that see plenty of people coming and going. Cornell University has an ace fact sheet to give you the lowdown on bed bugs. You can also have some fun playing around on Pest World for Kids, a website created by the National Pest Management Association (NPMA). But let’s get back to finding out why these wee pesky critters have returned and what makes them smarter today.
Gone But Not For Long
Here we have a bed bug hiding in a wood bed frame. The bed bug looks like it's having a Sunday snooze but I bet it's getting rest so it can hunt for fresh blood! Image credit: Thomas Oldani
Bed bugs were once nearly destroyed in our modern environment, where the use of chemicals such as dichlorodiphenyltrichloroethane – otherwise more easily known as DDT – kept these beasties at bay. DDT is a pesticide that is either very useful or very toxic, depending on who you ask or what journal study you read. Ultimately though, it was banned.
The Good And Bad Of DDT
DDT was used to keep mosquitoes under control, mostly because they spread malaria. It was used to keep lice numbers down too. So what happened when it was banned? As somewhat of a side effect of its use, DDT had kept bed bug numbers down. After it was banned, a bunch of other chemicals were used to treat bed bug infestations. The bed bugs, however, got smart and developed resistance to some of these chemicals. That resulted in a big UH OH for society as bed bug infestations are now on a major rise! Scientists from the University of Massachusetts Amherst and Korea’s Seoul National University decided that it would be important to find out more about resistant strains of bed bugs in New York. The work was published in the Journal of Entomology. Let’s see what they discovered, shall we?
When researchers got busy observing bed bugs in New York, they found these pests had mutations in their nerve cells. What does this mean? It means they are resistant to the chemicals used to kill them. Where the chemicals would previously have paralyzed and killed the bed bugs, the mutations mean that bed bugs are now outsmarting their opponents – us!
Let The Bed Bug Collecting Begin!
To get the scoop on bed bug resistance, researchers took a sample of easily controllable ones from Florida and compared these to ones from New York that were harder to deal with. So just how resistant were these little bugs?
Look at this partially engorged bed bug. It probably looks similar to the bed bugs in Milan after they feasted on my blood. Oh, and a fun fact of the day: the Italian word for bed bugs is cimice dei letti.
Researchers found that the bed bugs in New York had up to 264 times the resistance to the modern chemical used to kill bed bugs – deltamethrin. If we picture a nerve cell, it has these little sodium channels on the outer membrane bit. This is where the flurry of nerve impulses come to life. In the New York bed bugs, this nervous system mutation means they can keep feeding long after those Florida ones have been exterminated.
Grossaroo
When I was in grade 3, I made up the word ‘grossaroo’ to describe anything yucky. This word is fitting in the case of what happened to me recently when I was working at an agency in Milan. After a few nights at what seemed to be a nice corporate flat, I began to get loads of itchy, inflamed red bites. I awoke one night to find a flattened-looking bug moving across my otherwise clean, crisp white sheets.
I yelped and quickly squished it with my slipper, only to see it turn into a smattering of blood, which it just took from its recent feeding of my body! Just after, I saw another one. By morning, my bed looked like a crime scene with all those splats of blood and bugs. Eeek! Fortunately, I got moved to a new place and had everything washed. Hopefully, those Milan bed bugs weren’t too hard for the building owners to get rid of, unless they’re resistant beasts like those New York ones.
Bed Bug Warrior To The Rescue
So now you know (if you didn’t already!) that bed bugs do exist. Not only that, but they’re continually evolving to get smarter, doing so in ways that make it harder to get rid of them. For now, you can be smart by being extra cautious when traveling. Always check for signs of bed bugs around the mattress and furniture. Since not everyone shows bites from these little pests, prevention will remain the best line of defense. And while it’s not necessarily smart, it sure is fun when checking for bed bugs to yell “YOU’RE GOING DOWN!” If your parents ask what you’re doing, you can explain that you’re the self-appointed family warrior here to protect everyone from bed bugs.
Image credits: Unless otherwise specified, images courtesy of the National Pest Management Association.
The Recipe For A Perfectly Sticky Web May 31, 2009
Posted by Mrs Weird Scientist in Animals, Brain Power, Evolution, Insects, Tough Stuff.Tags: evolve, spider, web
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Have you ever tried to bake a cake, only to find out that when it came out of the oven, it was dry and hard? Maybe you realized that you’d put in too much sugar. Or, maybe you cooked it for too long. Would you believe that spiders have a similar challenge when it comes to spinning their webs? Too much of a good thing can actually leave a web that’s far from perfect.
For this web to catch its prey, it needs to have just the right amount of stickiness and strength. If all goes well for the spider, dinner will soon be served!
For a spider to catch its prey, the web needs to be sticky but still remain strong. If the balance isn’t right, the web won’t catch a bug and it’ll be one hungry and grumpy spider!
A Killer Web Evolves
If you’re a spider, you’ve got your work cut out for you! To catch your prey, you want a web sticky enough that the bug gets caught inside but strong enough that the web doesn’t break from its struggles. With such a fine balance needed, spiders have evolved to get it just right.
Let the Construction Work Begin
To build those impressive webs we see, spiders start by putting down lines of dry silk. Then, they weave spirals of sticky silk to nab their prey. But, spiders of yesteryear didn’t build their webs in quite the same way.
Millions of years ago, spiders would lay down a coating of dry adhesive on these spirals. Rather than stick to the web, a bug would be entangled by these dry spirals. As a cool fact you can throw out at your friends, there are still some spiders today that weave their webs with this dry adhesive – we call them deinopoid spiders.
Yet things began to change, with orb weaving spiders evolving to make webs that were more effective at catching prey. Rather than continue to use this dry adhesive, spiders started to go the sticky route by using wet drops of a glue-like substance. When you think of glue, it seems that the sticker the glue, the better. Not for spiders though!
Curious Scientists Start Investigating
Some scientists started to wonder about these sticky webs – is stickier always better? To find out, Ingi Agnarsson of the University of Puerto Rico in San Juan and Todd Blackledge of the University of Akron in Ohio went on a mission to check out a lot of different spiders. They observed 17 species of orb weaving spiders. You’d have to like spiders quite a bit to watch so many different kinds! The full study results are in the Journal of Zoology.
It’s All About Force
The researchers tested the strength of the strands and the stickiness of them too. How’d they do that? Well, they stuck a piece of sandpaper in the web and then measured how much force was required to remove it.
To break a strand on the web, a specific amount of force is needed. When the researchers put the web to the test, they found that by using anywhere from 20% to 70% of this force needed to break the web, the sandpaper was released.
So, a stickier web might hold the insect but as it continues to struggle, the force would ultimately break strands of the web, causing the insect to be released. Yet, with the glue being a bit less sticky, the insect could pull away from a single strand, but it would get caught by the next one. Since the strands don’t break, they can continue to stick to the bug, making its fight a much harder one.
Spiders Are Impressive
It’s actually really impressive and cool when you think about the work that goes into creating a web with just the right balance of stickiness and strength. As for me, I’ll leave the bug-catching to those smart spiders. I think I’ll just stick to making cakes instead. Pun fully intended! Now if only there was a recipe for making good jokes…
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It’s Good To Look Like Poo February 22, 2008
Posted by Mrs Weird Scientist in Animals, Insects, Tough Stuff.Tags: butterfly, camouflage, caterpillar, poo
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Sometimes, it’s great to look like poo. That is, if you’re a caterpillar! Say hello to the Asian swallowtail caterpillar. It has some neat tricks up its sleeve to successfully stay camouflaged from predators. The first trick comes into play quite early on – when the caterpillar is black and white, with fine spines. Here, it resembles bird droppings. Later on, the caterpillars get older and grow larger, which means it’s a lot harder for the caterpillars to pass themselves off as bird poo. So, as the little critters fatten up, their color changes to a vivid green. Hmmm. Why might being green work well as a camouflage? If you guessed it’s because they can blend in with the leaves, you got it!
Credit: Ryo Futahashi. You can see the wee caterpillar on the left side of the picture looks a lot like bird droppings! On the right, the distinguished fellow is a grown caterpillar – the bright, green color really does make the caterpillar look like the surrounding leaves.
Manipulating The Caterpillar’s Camouflage
In an interesting twist of events, Ryo Futahashi and Haruhiko Fujiwara of the University of Tokyo in Japan, discovered a special way to keep the caterpillar looking like bird droppings. This means that the caterpillar still matures and develops, but it retains its poopy camouflage instead of growing into a green caterpillar that resembles leaves. How did the researchers accomplish this task? It’s not so easy.
It’s All About Genes
You might already be familiar with the concept of genes. Your genes are unique instructions that tell your body how to work. They control all sorts of stuff such as your hair or eye color. Humans aren’t the only ones with genes either! Caterpillar camouflage depends on genes. There are three genes that control the caterpillar’s camouflage. One is responsible for the green color, another for the black color and finally, one for those spikes we see on the very young caterpillars.
Tinkering With Genes
If researchers can find a way to meddle with these genes, they can change the caterpillar’s color. Hint hint. In the case of our Japanese scientists, they did their meddling with a hormone that rules the expression of all three genes. It’s called juvenile hormone. Researchers smeared a synthetic version of juvenile hormone on the back of a young caterpillar. Since the hormone controls the three genes that affect the caterpillar’s color, adding more of the hormone managed to keep the caterpillar looking poopy right through its development. It’s a cool manipulation because it teaches us more about how hormones and genes interact. As for all this talk about poo, I think my next blog post will be on something a bit more pleasant!
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A Crafty Disguise February 6, 2008
Posted by Mrs Weird Scientist in Animals, Evolution, Insects, Tough Stuff.Tags: birds, fruit, nematode, parasite
3 comments
A very tricky parasite has recently been discovered. What makes it so sneaky? After infecting a certain species of ant known as Cephalotes atratus, the parasitic nematode triggers changes in the ant’s abdomen, which then becomes red and swells. This bulging, red appearance resembles a berry. Birds who feed on this type of fruit mistake the ant for a berry, swoop in and gulp! The bird swallows the ant, which allows the parasite to now infect the bird. Once birds are infected, the parasite can spread through the birds’ feces. In a bizarre circle of events, the ants round off the infectious cycle by gathering up the birds’ droppings so that they – along with their young – can feed off the feces. Smart parasite! It manages to sustain itself through the host ant so it can infect the unsuspecting birds – who think they’re about to eat a juicy, luscious berry!
Credit: Steve Yanoviak of the University of Arkansas. Check out the normal worker ant in the top picture and then compare it to the picture below it, which shows an ant infected with a parasitic nematode. That is one seriously red abdomen! It will be the doom of the ant when a bird mistakes it for a yummy, red berry.
Welcome To The Amazon
This peculiar cycle was observed in the tropical forests in the Amazon and Central America. Robert Dudley of the University of California – Berkeley described his surprise at finding such an intelligent series of events:
It’s just crazy that something as dumb as a nematode can manipulate its host’s exterior morphology and behavior in ways sufficient to convince a clever bird to facilitate transmission of the nematode.
The discovery itself was a chance one as Dudley, Yanoviak and Michael Caspari of the University of Oklahoma were observing a gliding species of ant. They noticed that some of the colony members had bright, red abdomens. Normally, birds don’t even eat ants – partly because of their yucky chemical taste. Yanoviak had some cool things to say about this fascinating discovery:
It’s phenomenal that these nematodes actually turn the ants bright red and that they look so much like the fruits in the forest canopy.
The full article describing the fruit mimicry will be published later this year in the journal American Naturalist. It might be worth a wee read to get the entire scoop on this amazing discovery. Also, research like this doesn’t go without funding – it was partially supported by the National Geographic Society, Amazon Conservation Association and the BBC Natural History Unit.
Evolution
I’m absolutely amazed at the findings. It’s incredible that something as seemingly simple as a nematode can manipulate the ants in such a successful way. It just goes to show that whether a creature is simple or complex, evolution can be one smart cookie!
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A Self-Destructive Mosquito Bite January 18, 2008
Posted by Mrs Weird Scientist in Animals, Diseases, Human Body, Insects, Think About It.Tags: insecticide, malaria, mosquito
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A mosquito’s bite usually has a characteristic sting, but the pain subsides and at worst, most of us experience a bit of swelling, itching and redness for a few days. For some people, however, a mosquito’s bite can bring with it some lasting discomfort – namely when the mosquito is carrying a disease such as malaria, yellow fever or West Nile virus – among others. The good news is that researchers from the University of Arizona in Tucson may soon have a way to make the mosquito’s bite deadly to itself!
Figuring It Out
Researchers recently discovered something very peculiar. When a mosquito species known as Aedes aegypti gorges on human blood, it excretes a substance called nitrogen immediately afterwards. The nitrogen is toxic to the mosquitoes and must be released following its meal. What happens if the mosquito doesn’t excrete the nitrogen? Bam! Self-destruction! If the mosquitoes don’t excrete the nitrogen, they will not lay eggs and will most likely become ill and die.
Taking Advantage Of Nature
By taking into account this complicated metabolic pathway of the mosquito, researchers are now looking for a molecule that won’t harm humans but will basically muck up the metabolic pathways of mosquitoes, which means they’ll retain their nitrogen and effectively self-destruct. Once the researchers have figured out the mechanics of the molecule, they can then develop an insecticide and spray it in the areas where mosquitoes like to play – around the water, for example.
According to the lead researcher Roger Miesfeld:
Our goal is to turn the female mosquito’s blood meal into the last meal she ever eats. The whole community would essentially become one big mosquito trap. It would be a group effort that in the long run could have a huge impact. This would be one more weapon in our arsenal against diseases that kill millions of people a year.
Another potential application would be an oral insecticide. So, if you lived in an area where a disease such as malaria is prevalent, you could take a pill that would cause the mosquito to ingest the insecticide along with your blood. This wouldn’t prevent you from actually getting the disease but it would kill the mosquito after it bites, which means the spread of disease could be slowed.
I find it easy to forget just how potentially dangerous a mosquito’s bite can be, mostly because I am either living in North America or the United Kingdom, where the risk of disease from mosquitoes is fairly small. Yet, for many people, diseases passed through mosquitoes are a frightening reality. Hopefully, this new research can help to reduce the mosquito population and prevent both the initial sting and the spread of diseases.
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Honeybees Aren’t Always So Sweet January 3, 2008
Posted by Mrs Weird Scientist in Animals, Easy As Pie, Insects.Tags: bees, hornet, wasps
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Credit: Papachristoforou et al. for New Scientist.
I have an interesting and sometimes rocky relationship with the buzzing creatures we call bees and wasps. Like some people, I retreat when I see the odd bee nearby – even as I take care to avoid being stung.
At one point in time, I even developed an intense fear of wasps. What triggered my fear? I lived in a top floor flat in Scotland for a year. During this time, a wasp’s nest emerged, which was likely somewhere near the building. Despite calls to my landlord – who had workers searching for the elusive nest – nobody could find the exact location of these persistent insects. For weeks, I (along with my similarly frustrated neighbors) had wasps coming in from every nook and cranny around the windows and vents. I remember sitting at my laptop, attempting to type up a laboratory experiment while wasps perched on my curtains, flew around my lights and generally had me grumbling at the presence of these new, unwanted flatmates. A visit from a local handyman resulted in duct tape all around any openings in the flat, which ultimately sealed me in the flat and kept the wasps out!
Fortunately, enough time has now passed that I am more fascinated than fearful of these little creatures. I saw this video recently and wanted to share it here on the weird science blog. In this video, loads of Cyprian honeybees swarm around a hornet to suffocate their enemy. Trust me – when I say swarm, I mean it!
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An Enormous Spider Web September 1, 2007
Posted by Mrs Weird Scientist in Animals, Easy As Pie, Insects.3 comments
Most of us have probably seen the odd spider web glistening in the sun. Perhaps you’ve even walked into one and felt its fine, long threads tickling your face. If you’re one to shy away from spiders or are deathly afraid of them, you may not want to read on!
Welcome To Texas
A massive network of webs has been identified in Lake Tawakoni State Park, which is located in Texas, United States. So just how massive is this network of webs? Well, the spiders have been spinning their webs over several acres of trees in the park. One local insect biologist describes the occurrence as very unusual and explains that the main spiders found are long-jawed spiders. This is particularly unusual because long-jawed spiders aren’t social spiders, which are the ones who will normally build communal nests in other areas. Also, this kind of thing is more likely seen in the tropics, not Texas. The expansive webbing is similar to a canopy, spreading across trees in the park.
Figuring It All Out
For now, experts are analyzing the spiders to find out more about this enormous network of webs. So far, several species of spiders have been identified in the webs – not just the long-jawed type – including big garden spiders. Most of the experts agree that this is something none of them have ever seen before. It’s also not something one would necessarily want to walk under either. With my long, curly hair, a lot of those spiders could fall onto my head and I’d have a hard time finding them all! Eeeeek.
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World’s Snappiest Creature Award August 6, 2007
Posted by Mrs Weird Scientist in Animals, Easy As Pie, Insects.add a comment
The award for the world’s snappiest creature goes to the termite. A measly little creature, it snaps its jaws with a strength and speed rivaling all other animals. Formally known as Termes Panamensis, the termite’s jaws have some special properties that provide its power and speed.
Who Figured That One Out?
The news was recently announced at the Eighth International Congress of Neuroethology in Vancouver, Canada – close to home for my fellow British Columbian readers. Marc Seid and Jeremy Niven of the Smithsonian Tropical Research Institute in Panama filmed the termite’s jaws at 40,000 frames per second, showing a speed of 70.4 meters per second over a distance of 1.76 millimeters!
A Threatened Termite
When challenged by an intruder, a termite will use four sets of enormous muscles to aggressively smash the bits of its mouth together. In fact, these muscles are so massive that they take up half the space in the termite’s head. All of this power and force then lets the termite rapidly snap at the intruder. Also, the termite’s teeth work like a saw, biting with razor-like strength, which is propelled by those strong muscles.
Now don’t go and get any ideas about trying to beat out the termite by practicing your own snapping skills. I really don’t need any of your parents emailing me to complain about your chipped teeth!
Credit: Pictures provided by the United States Department of Agriculture: Agricultural Research Service.
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