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!

katydid 012

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.

Feb2010 069

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!

Feb2010 084

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!

For all the future Entomologists out there…

We recently got an e-mail from a young man named Derek. Derek is 13 years old and came across our video “Meet the Entomologists of the Cockrell Butterfly Center” on YouTube.  He is interested in becoming an Entomologist and must have been intrigued by what he saw. He had some questions for me about my career. I’m always happy to answer such questions and if you have an interest in a career in this field, maybe my answers will help you too!

Here’s what Derek wanted to know:

1. This is a dumb one, but how much do they make yearly?

Eyes of a Holcocephala fusca Robber Fly
Creative Commons License photo credit: Thomas Shahan

This is certainly not a dumb question and can be an important issue, especially if you have student loan debt, like me! Yearly salaries vary, depending on what exactly it is you are doing. As an entomologist, you can work at a variety of different jobs. You can work in a museum like myself, or be a pest control operator, work for the government, in a lab, as a professor, the list goes on and on really. Whatever you do, you should not expect to make 6 figures and you may start off with a lower salary than you’d like, but the longer you are in the profession and the better you do, the more valuable you become and the more money you will make! I am very very happy with the money I make and most importantly, I LOVE my job. There is no amount of money that could replace that. Rest assured, if you become an entomologist, you will have a fun and rewarding career and you’ll make plenty of money!

Visitors of the Prayerful Sort
Creative Commons License photo credit:
Clearly Ambiguous

2. Can you specialize in a specific insect? I am very fond and know a lot about the praying mantis.

This also depends on how far you go in school and what career you choose. A lot of entomologists that go for their PhD. specialize in a certain insect and study them in a lab at their universities. I personally have a lot of freedom in my job. I have hundreds of different insects that I care for here and I can choose to study any one of them in greater detail. I also love praying mantises, they are definitely one of my favorites! I spend a lot of time raising them and studying them. I could at any time choose to do a research paper or even write a book about them if I really wanted to! In other jobs as an entomologist, you may be more limited, so if I were you I would do a lot of research on what type of entomologist you want to be.

3. Did you ever receive a sting or a bite that can kill you? I don’t care if it hurts.

A Centipede on display at HMNS

Well, you know Derek, insects are not as dangerous as many people think, and a lot of it depends on your own body’s sensitivity to certain types of venom. We do have a bee colony here, and  if I were allergic to bee stings, a sting could probably hurt me or put my life in danger if I did not get the right kind of medical attention. Luckily, I’m not allergic to bees, but if I was, it would not discourage me from working with them because I know how to treat them respectfully and avoid being stung. And we take care to make sure our visitors can’t come in contact with them. We really do not have any insects here that are highly venomous, because there really aren’t many out there. Now other arthropods are a different story. We do also have arachnids such as spiders and scorpions and centipedes. All of these animals are venomous, but none that we have are deadly, although a bite from our giant centipedes can land you in the emergency room! I always take certain precautions when working with these animals, just like someone who works with venomous snakes. That being said, I have been bitten, scratched, poked, pinched, and even had venom spit into my eye. None of these were a big deal, I never had to go to the doctor or anything, but they were all learning experiences!

How many insects do you work with or study a day? And for how long?

Capturing Grasshopers on Film in Costa Rica

Well, you could say millions if you add in all of the ants in my various ant colonies! Thank goodness every ant doesn’t need individual attention! I spend a large part of my day with basic care of the insects in the Insect Zoo and Containment Room where I have hundreds of insects. I spend a lot of time just feeding them, making sure they have enough humidity, cleaning their habitats, etc. That stuff is a lot of work, and unfortunately, doesn’t leave a lot of time for study. My day is also taken up with other things like writing e-mails, answering phone calls, leading tours, taking the bugs to schools for our outreach program, and just generally educating people about bugs. So that’s what I do with my time from 8-5 Monday through Friday. Now, like I said before, I can study certain bugs if I’d like to and I do make time for that because every year I get the chance to write a research paper and present it to other entomologists at a conference. This year, I’m working on a paper about the Giant Katydid (Macrolyristes corporalis) which is such an amazing insect. I’ve already written a couple of blogs about it. To me, this career is very unique because I’m not just stuck in a lab.  I am kind of like a teacher, consultant, scientist and caretaker all rolled into one, which makes for a very fun and interesting job! I even get to travel! In 2008, I got to go to Costa Rica to see bugs in the rainforest, it was awesome! I learned all about bugs in college, but I’ve learned far more here from actually getting to work with live insects and observe their life cycles and behaviors. A lot of labs are full of dried specimens of dead bugs, which can be cool too, but I’m very happy to be here!

5. Finally, how would I become one? To be honest, I don’t know many colleges or schools that practice entomology, and you just don’t see ads in the paper for entomologists! Good question! Well, I went to Texas A&M for college and it is the only University in the state of Texas from which you can receive a degree in Entomology. I’m not sure where you live, but in most states, there is at least one university that offers this type of degree. The internet is a great resource for this, just google degree programs in Entomology and that should get you started. Next, you will have to decide how far you want to go, I only have a bachelors in Entomology just because, for now, I can’t afford anymore college, but I plan to get a masters someday soon and eventually a PhD. In college, you will have so many resources available to you that will help you figure out what jobs are available and what you want to do. Like I said, there are so many different things you can do with a degree in Entomology. These jobs can take you anywhere in the country, even several places around the world! You can even do my job almost anywhere. Most states in the U.S. and even countries in Europe, Asia, Australia and South America have museum with insects zoos and butterfly houses much like ours and they always need good Entomologists!

Well Derek, I hope this helps you! My best advice is to keep doing what your doing and studying insects. You may have people, even family members and friends tell you that Entomology is not a good career choice. Only because most people don’t know much about Entomology, or even bugs in general, but don’t let that discourage you. If you work hard and do well in school, you can do anything you set your mind to and I’m sure you will be a successful and happy Entomologist, just like me! If you have anymore questions, or any other budding entomologists out there for that matter, please feel free to contact us by sending an e-mail to blogadmin@hmns.org. Happy bug watching!

Merry Christmas Butterfly

I thought that for this month I would share with you a very special butterfly called the “Christmas Butterfly.” I have no idea why it is called this; it’s not green or red and it doesn’t sing carols or light up, but it’s beauty does make you smile the way that Christmas does! I actually got a phone call a few years back about why this is called the Christmas butterfly. I had never heard of this festive name, so I searched and searched for an explanation but came up empty.

The scientific name of this butterfly is Papilio demodocus. (You can see a great picture of one here.) The other two common names of this species are the orange dog and citrus swallowtail. This butterfly is native to Africa and is a common pest of citrus trees. We used to receive a similar species of butterfly, Papilio demoleus, from the Philippines, but the USDA has completely taken it off any permit because it is such an awful citrus pest. If that butterfly was to get out of the Butterfly Center it would most likely die, but it could also completely demolish our citrus groves here, so better to be safe than sorry!

The Christmas butterfly is a member of the Swallowtail family, Papilionidae. Caterpillars in this family are super cool because they all have this weird organ behind their head that they use for defense called the osmeterium. This organ protrudes from the back of the caterpillars head when it is threatened to ward predators off. It is forked, sticky, smelly, and reddish-orange in color. The picture below is of a Thoas swallowtail caterpillar, Papilio thoas, taken here inside the Butterfly Center when some caterpillars unexpectedly showed up on one of our plants.

The Christmas butterfly caterpillar starts off brownish black and white in coloration and it very closely resembles bird droppings. As the caterpillar gets larger, it changes to a bright green color. The chrysalis has awesome camouflage. It looks just like a small branch on a tree that a stick was broken off of.

Well, that’s about all I have this time. I hope everyone enjoys the holiday and has a Merry Christmas Butterfly!!!

Bug-crazy? Learn more:
Check out this video to Meet the HMNS Entomologists.
Have you noticed – where have all the bugs gone?
Learn how to pin a butterfly.

The Sphinx Moth: A Work of Art

Today we have a special guest blog from Chad Erpelding, Assistant Professor of Art at Stephen F. Austin State University in Nacogdoches, Texas.  He teaches 2D Design and Painting there.  This fall the Cockrell Butterfly Center is hosting an exhibit of some of his students’ paintings that were inspired by sphinx moths.  Here is what he has to say about the project.

The overlap between art and science is a subject rich with potential and currently being investigated by many artists.  Damien Hirst suspends animal specimens in large tanks of formaldehyde.  Olafur Eliasson, who is currently having a major survey of his work at the Dallas Museum of Art, explores weather systems and natural phenomena.  Mel Chin worked closely with a scientist in realizing his piece Revival Field, which uses plants to remove toxic metals from a polluted site.  So when Dr. William Godwin, entomologist at Stephen F. Austin State University and adjunct curator at HMNS, brought up the idea of a joint project between the Biology Department and the School of Art at SFA, I jumped at the opportunity.

We decided to organize a competition for the art students centered on sphinx moths (family Sphingidae), several members of which are found locally in Nacogdoches and throughout east Texas (see Nancy’s recent blog on these fascinating moths.)  Dr. Godwin gave a lecture on the characteristics and life cycle of sphinx moths, giving the students the base of knowledge needed to understand their subject.  From here, I stressed to the students the importance of finding the balance between accuracy towards the moths and the inventiveness that happens in the studio.  The restrictions we put on the entries were only on size and weight of the pieces themselves.  We wanted the students to have the freedom to explore their own interpretations and realize their creative impulses. 

I was thrilled with some of the pieces the students created. Carolyn Norton, a graduate student from Lufkin, won first place for her piece “Sonic Defense,” an ink drawing that follows the paths of a bat and moth in battle, including an explosion of scales – a trick that moths do to fool their predators mid-air. 

Margaret Pledger, a senior from Brenham, received second place for her “Pupa Ring,” a copper ring based loosely on the shapes of sphinx moth pupae.  Chad Hines, a graduate student from Temple, received third place for his “Sphingidae,” a drawing that simultaneously explores the patterns of the moths and the joys of making marks on paper. 

The truly fascinating part of this project for me was to see the many different directions that the artists took.  You never know from where inspiration will come.  While some of the students looked at the patterns and shapes of the moths, others were interested in their habits or specific characteristics.  A few explored broader cultural connections, using the moths as a metaphor for the human experience.  Whatever the source, I think this was a great opportunity for both the science and art communities to see how our fields can interact.  It encourages us to continue to see the world in new and awe-inspiring ways.

Please be sure to stop and take a look at these interesting works of art on your next visit to the Butterfly Center.  They are in the lower level (just around the corner from the mosquito display) and will remain on display until March, 2009.

Sphinx Moth art, on display in the lower level
of the Cockrell Butterfly Center.