In My New Skin

Yao Ming
Creative Commons License photo credit: Keith Allison
Yao Ming –
The guy just didnt stop growing.

I bet you’ve never thought of growth in as much detail as I have. As an Entomologist, I think about it a lot! It’s very simple for vertebrates. You eat, drink and sleep – and your body grows. Do you tell your body to grow? Do you try to grow? No, it just happens, slowly at times and quickly at other times. Sometimes we grow up and unfortunately, sometimes we grow out! The point is that it is an involuntary action that our body undergoes, just like breathing, blinking, salivating and blood pumping! I am so grateful to be a human and have this happen effortlessly and without many bumps along the way.  Arthropods, on the other hand, got the short end of the stick! Arthropods have to go through a serious ordeal to get from one size to another, known as molting or more scientifically, ecdysis.

Insects and other arthropods are not like us, obviously! Whereas we have an endoskeleton, or skeleton that supports our body from the inside, they have an exoskeleton, or a hard shell covering the outside of their bodies. This exoskeleton functions much in the same way as ours does. It supports the arthropod, as well as acting as a point for muscle attachment. Additionally, it protects them from certain predators and parasites and helps to keep terrestrial arthropods from desiccating or drying out. It also contains certain sensory structures that are very important to insects and their many relatives.

Exoskeletons are formed by a long chain polymer called chitin. This compound is very tough and resilient and is also found in other animal structures such as the beaks of octopi and squid. When I’m teaching kids about exoskeletons, I like to compare it to a suit of shining armor that a knight would wear. Now, if it was a young knight, he would have to grow, so he could not always wear the same suit of armor. He would have to trade it in for a new, larger one. This is the case with arthropods and their exoskeleton. In order to grow and get larger, they must shed their exoskeleton and grow a new one.

This is where things get a bit hairy! In order to shed their exoskeleton, arthropods have to go through a scientific process called ecdysis. I’ll spare you the boring scientific details, but basically, they excrete a liquid that separates their old skin from their bodies. This process is called apolysis. They then form a new skin. They excrete another chemical which digests the innermost layers of the old skin and they crawl out of what’s left. What’s left behind turns into a dry crunchy empty shell. Shortly before this process, arthropods stop eating, start swelling up a bit, and eventually stop moving or being able to function at all. If anything at all goes wrong during this process, they are finished!

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Creative Commons License photo credit: emills1
A katydid nymph molting,
getting a little help from a friend!

Many insects have to hang upside down and let gravity help pull them out of their old exoskeletons. If they fall from their perch before they are done, they will not be able to get everything out and will either die or be severely deformed. To make matters worse, they are super defenseless during and after this process, making them prime targets for predators! If an arthropod is able to successfully complete their molt, they are stuck with this brand new, super soft exoskeleton. They can neither walk nor fly. They are completely vulnerable for at least a couple of hours. Have you ever eaten soft shell crab? Well, it’s not some cool different species of crab you’re eating, it’s just a regular crab that has been harvested right after molting. They cook it while it is still soft, so you’re eating the whole crab, shell and all. I can’t ever bring myself to eat them, it kind of grosses me out! The most commonly used crab for this, in the United States, is blue crab.

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Creative Commons License photo credit: emills1
A deformed katydid due to a failed molt

If the arthropod is able to successfully remove all body parts and limbs from the old skeleton and find a safe place to rest until their new skeleton hardens, they can go on living their little bug lives, until the next time they have to molt! This process gets even more complicated in insects that have what we call complete metamorphosis, such as butterflies, beetles, flies and bees. Insects like grasshoppers, cockroaches and praying mantises go through incomplete metamorphosis, so every time they molt, they have relatively little changes in their bodies. They mainly get bigger and some grow wings. As we all know, a butterfly starts out as a caterpillar, it gets bigger as it molts, but when it’s time for it to pupate or form a chrysalis, the process of molting involves the insect changing its body completely. This makes it even MORE of a challenge for them.  It’s very interesting to note that similar chemicals that digest the insect’s old exoskeleton, digest most of the actual cells of the larva, leaving only some cells alive. These remaining cells reform the organism into a completely different looking organism, like the adult butterfly!

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Creative Commons License photo credit: emills1
The Exuvia of a Giant Prickly Stick,
a walking stick from Australia.

The cast away skin of an arthropod is called the exuvia or exuvium. When it’s first removed from the animal, it’s soft, like the new skin, but as it dries out, it becomes very crunchy!

I bet almost everyone has seen one of these. You know those empty insect shells you can sometimes find stuck on trees? I grew up calling them locust shells and I used to love scaring my siblings and friends with them. Then I’d get a lot of pleasure out of crumbling them up! Well, they are not locust shells; locusts are a type of grasshopper. These exuviae belong to cicadas.

Tibicen Cicada
Creative Commons License photo credit: jasonb42882
A cicada molting.

Cicadas are those funny looking insects you hardly ever see but always hear in the summer. You can hear the rattling noise they make during the hottest hours of the day. The immature cicadas can spend anywhere from 2 to 17 years feeding on tree roots underground, depending on the species. They emerge at night, start climbing a tree, and complete their final molt to adulthood on the way up. The next day we find the shells, but the actual cicadas are high up in the tree tops by then!

Every arthropod on the planet has to go through metamorphosis that involves molting. Insects, spiders, centipedes, millipedes and crustaceans. Interestingly, millipedes are born with only a few segments and legs. Each time they molt, they add another segment and 4 more legs.  I could go on and on about the amazing molting process. The point is, next time you are getting down about anything in your life, think about how easy we have it compared to the bugs of the world. Be thankful that we have easy access to resources we need to survive, we have no real predators and we don’t have to molt! The whole process terrifies me really, so I’m very thankful!

Until next time, happy bug watching!

Photo From You:Insect Identification

Photo submitted by Alex

Last week we got an interesting photo from a man named Alex in Guanajuato, Mexico. At first glance it looks like a stem with green thorns and some really weird, spiky, alien-looking bugs. The “green thorns” are actually insects that often get dismissed as, well, green thorns! These little guys are called treehoppers and they are everywhere, constantly being overlooked because of their excellent camouflage. They belong to the order Homoptera, which is notorious for containing almost all of the worst plant pests, including everyone’s favorite, the aphid! This order also includes interesting, non-pest insects like the cicada and the masters of disguise, treehoppers and leafhoppers. Most entomologists today lump the order Homoptera with Hemiptera, or true bugs such as stink bugs, leaf-footed bugs, and assassin bugs. I, however, think they’re different enough to have their own group.

So, as I said, most treehoppers are not considered pests except for a small handful, including this little guy, the Keeled Treehopper (Antiathe expansa). They are known to attack plants in the family Solanaceae – especially tomatoes, eggplants and chile peppers. Alex found these guys all over his chile plant! In large enough numbers, they can seriously injure and even kill these plants. The problem is that, unlike more efficient insects like butterflies, beetles and flies, the young nymphs and adults eat the exact same thing. They use a sharp beak to penetrate the tissues of plants and suck the sap. All homopterans feed this way and that’s why so many of them cause damage to plants. All of this sap eating causes these insects to excrete a sugary liquid called honeydew which ants go crazy for! The ants will “milk” the honeydew from the homopteran and in return for the yummy snack, protect them from other predators. For example, ants who farm aphids for honeydew will keep the hungry ladybugs at bay to protect their precious nectar. For this reason, ants are very often associated with homopterans.

Creative Commons License photo credit: Dvorak319
treehopper being farmed by ants

So, what are the little spiky, weird orange guys? You guessed it, the nymphs! Very often, treehopper nymphs will look very different from the adults, but as time goes by, with every molt, they will lose their spines and start to resemble the green thorn-like adults. Treehoppers come in a wide array of fascinating and even downright bizarre shapes and appearances. Those found in the tropics are a bit larger and sport vibrant colors and odd protuberances unlike any other insects. Next time you are out and about, look a little more closely, and you’re sure to spot them!

Remember, if you find an odd looking bug and would like to know what it is, snap a picture and send it to us at blogadmin@hmns.org. Happy bug watching!

New Addition to the Cockrell Butterfly Center!

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Phyllium giganteum
Creative Commons License
photo credit: emills1

Today was an exciting day here at the Butterfly Center, as we welcomed a new species, Phyllium giganteum. This is a type of walking stick or phasmid that is native to Southeast Asia. We have a relative here already, Phyllium celebicum. We have enjoyed them immensely as they are very attractive on display and calm enough to go out with our Bugs on Wheels program and visit children. People are absolutely taken aback by how much they resemble a leaf, and most visitors are drawn to this particular insect since it resembles such a harmless object.

Well, if you were blown away by our original leaf mimics, hold on to your hats and meet Phyllium gigateum! While celebicum can reach a modest 2-3 inches, giganteum is an impressive 4-5 inches long! The flaps on skin surrounding their legs and abdomen are very broad with brown edges that match a dying leaf.  You really need to meet these guys in person!

Well, I should say girls. This species is parthenogenic in captivity, meaning they don’t need to mate to have babies. Males are rarely seen, even in the wild. Each female can lay a couple hundred eggs which take about 5 -6 months to develop.  The eggs are dropped to the ground by the female who dares not leave the safety of the canopy. When the nymphs hatch, they scurry up the tree, hopefully fast enough to avoid being on someone’s menu.

You may be wondering why these phasmids have such a camo-advantage while other harmless insects are much easier to spot. If an insect is lacking in the camo department, you can bet it has one of many other safety features including: being able to run or fly very quickly (cockroach), having  a very hard exoskeleton or one covered in spines (beetle), being poisonous or distasteful to predators (lubber grasshopper), having the ability to emit or even project a noxious chemical (swallowtail caterpillar), or the ability to mimic something dangerous or show a scary display(giant prickly stick). An insect’s life is pretty much all about escaping predators among other dangers of the natural world! Phyllium can do nothing else mentioned above, so it’s all about the camouflage for them!

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a giganteum nymph
Creative Commons License photo credit: emills1

Caring for these insects is easy. I only have to meet their basic needs of food, warm temperature, and high humidity. Luckily, they will eat a variety of plants that can easily be found right here in Houston. Since these insects are parthenogenic, raising them should be a snap! We hope to have them as a permanent fixture at the Butterfly Center for years to come.

I hope you will come see them on display or be excited to have one visit your child’s classroom in the very near future. Fall is upon us now and winter will be here before you know it, so bugs everywhere will be chilling out for the season, not to be seen again until spring. So if you want to see some great bugs, native and exotic, pay us a visit! Until next time, happy bug watching!

Katydid…She Did!

Since writing my blog “Katydid…Did She?” I have been overwhelmed by the amount of feedback I’ve gotten. Apparently, katydids are a very popular insect and I have heard stories and answered questions from readers as far away as Bangladesh and London.  I am so happy to share my love of insects with people around the world! Katydids have given mothers a way to bond with their children, been a companion for people seeking  an easy pet to care for, and inspired curiosity and wonder in so many.

Green Katydid
Creative Commons License photo credit: Gerald Yuvallos

One great story came to me from a gentleman named James from London.  He had acquired a male and female pair of katydids from an entomology show. After having them for several months, the male passed away. The female seemed, he said, to be very sad. She was making an awful lot of noise and quickly laid several eggs, then died shortly after, dragging her weakened body to lay next to her mate. It seemed romantic that she had died of a broken heart.

I gave him some suggestions on how to properly care for his new eggs.  A short 5 weeks later, the first little hatchlings started to emerge. I was so happy to hear this news!  He sent me a few photos of his new babies for identification and they were adorable. I was surprised to find out that they were a species from Florida, Stilpnochlora couloniana. A beautiful and large species native to our own country! This is just one of so many great stories that readers have shared with me.

So to all of my readers out there that are crazy about katydids, I have wonderful news! The inspiration for my very first post about katydids, giant Malaysian Katydid ( Macrolyristes corporalis)  eggs, have finally hatched! This was a newer batch that was laid in mid- November. For months I have been doting over them and hoping that they would hatch. On Thursday, March 5, I found my first brand new little nymph. I was absolutely overjoyed! I now have 11 nymphs with 20 more eggs to go.

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Creative Commons License photo credit: emills1
one of my babies!

These tiny little katydids have to shed their skin 6 times and in about 6 months they will have grown into the largest and loudest species of katydid. Right now they are very goofy looking. A tiny little body with extremely long skinny legs and antennae that are several times the length of their bodies. Once they reach adulthood, they will be put on display for visitors to see and travel to schools all around Houston to amaze children and teach them the wonders of the amazing world of insects! I would like to thank all of the readers who sent in their comments and stories and would love to hear more! If you have  anything to say at all about katydids or insects in general, feel free to leave a comment, they are always appreciated! To all of you insect enthusiasts out there, happy bug watching!

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Creative Commons License photo credit: emills1
One of our majestic Giants