Collecting Butterflies

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In 16th, 17th and 18th centuries, world exploration was exploding. Return voyages from far postmarks and lands with strange names yielded curious specimens of plant and animal. Naturalists rushed to collect and name these species, working to figure out how one might be related to another. The cabinet of curiosities became the manner of exhibition for the collections of naturalists. Tiny museums of the strange, these cabinets housed butterflies and corals, snakes preserved in alcohol and pressed flowers, shells of all manner and species like the platypus that confounded the naturalists of the day.
The collection of butterflies was all the rage in the Victorian era. With bicycle and train, the average person could take off for the county and armed with a net, a killing jar and some pins, return with a box of mounted butterflies. In the mid 19th century there were some 3,000 avid butterfly collectors in England alone.
In recent times, a stigma has become attached to those who would collect and kill butterflies. The collecting and killing of butterflies is not illegal, with the exception of a selection of protected and endangered species whose numbers in the wild are already concerning low. Butterfly collection in the past seems to have played no significant role in the declines of butterfly populations, rather habitat loss is often cited as the cause.
Today, butterfly collecting is more often done in the form of photographs taken by butterfly enthusiasts who scour empty urban lots and virgin forest for the chance to site and digitally capture the beauty of a butterfly. For those who would still collect mounted butterflies, specimens are readily available from butterfly farms around the world rather than collected from the wild.

Great Collectors and Huge Collections

Walter Rothschild, the brother of Charles Rothschild, obsessively collected more  than two million butterfly specimens before his death in 1937, nearly bankrupting his family. His collection forms a significant portion of the largest butterfly collection in the world, housed at the Natural History Museum in London. This amazing collection is still yielding new information on butterflies and moths and new species are still being found within the collection. Walter’s younger brother Charles Rothschild gifted his entire butterfly collection of 3,500 specimens to his alma mater, the Harrow School in 1900.
Dr. William and Nadine McGuire donated their collection of some two million butterflies specimens to the Florida Museum of Natural History. The donation of this collection brings the number of butterflies in the museum’s collection to about nine million. The butterfly collection at the McGuire Center for Lepidoptera and Biodiversity is now considered the second largest in the world.
The U.S. National Entomological Collection houses some four million specimens of Lepidoptera from around the world.

Read More

Read more about collections, collectors and cabinets of curiosities:

• Albertus Seba Cabinet of Natural Curiosities by Irmgard Müsch, Jes Rust and Rainer Willmann
• The Species Seekers: Heroes, Fools, and the Mad Pursuit of Life on Earth by Richard Conniff
• Dry Storeroom No. 1: The Secret Life of the Natural History Museum by Richard Fortey
• Stuffed Animals and Pickled Heads: The Culture and Evolution of Natural History Museums by Stephen T. Asma
• Mr. Wilson's Cabinet Of Wonder: Pronged Ants, Horned Humans, Mice on Toast, and Other Marvels of Jurassic Technology by Lawrence Weschler
• The Dangerous World of Butterflies: The Startling Subculture of Criminals, Collectors, and Conservationists by Peter Laufer
• The Aurelian Legacy: British Butterflies and Their Collectors by Michael A. Salmon
• Winged Obsession: The Pursuit of the World's Most Notorious Butterfly Smuggler by Jessica Speart

A Summertime Walk in the Back Woods

The 25 acres of MOSI’s Back Woods is an unexpected oasis of nature in the middle of a heavily urban area. The Back Woods offer wetland habitats, upland forest and sand hill habitats, and more, with a shell trail, boardwalk, and sand trails throughout. Its a quiet place to look for small mammals, butterflies and other insects, and interesting native plants as you enjoy a peaceful stroll. Enjoy the pictures from our recent walk, and feel free to stop by and take a walk in the Back Woods yourself one day soon!

Jill’s Photo Album:

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Kristen’s Photo Album:

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A Summertime Walk in the Historic Tree Grove

MOSI’s Historic Tree grove is filled with trees tied to famous people, places, and events. A stroll through the gardens allows you to visit an American Redbud descended from one outside Clara Barton’s office, a magnolia from the grounds of the infamous Civil War-era Andersonville prison camp, a sycamore whose ancestors have been to the moon, and many more. Learn more about the Historic Tree Grove here, and click through the albums below to see what’s going on in the gardens around the trees this time of year.

Jill’s Album:

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Kristen’s Album:

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A Summertime Walk in the Butterfly Garden

Here at the MOSI BioWorks Butterfly Garden, our small staff size means we’re pretty constantly busy, especially in the summer months when weeds grow like… well, weeds. We do our best each day to stop and admire what’s around us, though. Here are pictures from each of us from a recent stroll through the Flight Encounter and outside Butterfly Garden. (Click the links to view the full albums with captions.) Look for more pictures later this week of our walks through the Backwoods and the Historic Tree Grove.

Jill’s Album:

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Kristen’s Album:

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Carolina Wild Petunia

Carolina Wild Petunia (Ruellia caroliniensis) is found in wild woodlands from Virginia to Texas. As you might expect from a forest wildflower, this plant does best in part to full shade. Several patches grow beneath the trees in the Butterfly Garden behind the BioWorks Flight Encounter here at MOSI.

Wild petunia is very drought-tolerant. It begins flowering in spring and, under the right conditions, will continue to flower throughout the summer and fall, although not quite as robustly during the hottest summer months. It’s a small bushy plant, growing to a height of about 18 inches. A perennial in zones 6 – 10, it’s generally killed to the ground in a freeze but quickly returns. It spreads freely by seed, but small seedlings are easy to remove by hand so it’s unlikely to take over a space.

It’s a great wildflower in a wildlife garden. The pretty purple flowers are pollinated by bees and visited by butterflies, and the leaves themselves are a host plant for the Buckeye butterfly caterpillar, a common visitor to our area every spring.

Like many natives, Carolina Wild Petunia is hard to find outside of nurseries specializing in natives. Thought it grows fairly easily from seed, seeds are rarely available for purchase. If you know someone who grows this plant, you can ask if they have seeds or seedlings they’d be willing to part with.

Be careful when asking for this plant at nurseries. Another ruellia species, non-native Ruellia brittoniana, is commonly available for sale and is VERY invasive. Known as Mexican Petunia, it spreads by deep runners that are nearly impossible to get rid of. (Learn more here.) As for true petunias (Petunia x hybrida) which are available in a range of colors and sizes, they are native to South America and not closely related to our wild petunia. Though not invasive, they are generally treated as an annual in the U.S., rarely returning the following year.

Butterflies in Bad Weather

When skies begin to darken before a rainstorm, just like when the sun sets at evening, butterflies seek shelter. This may be clinging to the underside of a leaf like the Julia Longwing in the photo. Other butterflies can be found deep within a stand of grasses or perhaps tucked under a man made overhang on a building. Rain is a big deal to a butterfly.
If you are a butterfly, rain is not a great deal of fun: The average monarch butterfly weighs in at around 500 milligrams. The average raindrop weighs a bit more than 1/7th of that, around 70 milligrams. Scientific American suggested that the impact of a raindrop on a butterfly would be similar to a human being hit with a water balloon with twice the mass of a bowling ball. Ouch.
During periods of high winds, butterflies will also seek shelter. Sturdy shrubs and trees become great butterfly shelter during strong storms and hurricanes. As soon as the rain has quit, the wind died back and the sun has returned, butterflies leap from their hiding places to continue patrolling, courting, egg laying and nectar sipping. What a life.

Metamorphosis

Precisely what happens during metamorphosis? It is not the easiest question to answer, but here we go. Let's talk metamorphosis.
The picture here is of an Orange Barred Sulphur chrysalis about one day before the butterfly emerged. Looking closely at the greenish leaf-shaped pod you can see some of the wing markings of the butterfly within, which are some of the last details of a butterfly to form during metamorphosis. Prior to this, a lot is happening in that tiny pod.
From the outside it appears as though the pupa, also known as the chrysalis, is resting. In reality the larval tissues completely break down and reorganize rapidly within the pupal skin.
The first thing that happens is that a lot of the caterpillar’s old body dies. It is attacked by the same sort of juices the caterpillar used in its earlier life to digest its food and it would not be wrong to say the caterpillar digests itself from the inside out. This process is called ‘histolysis'. Not all the tissue is destroyed and some of the insect’s old tissue passes on to its new self.
There is one particular sort of tissue left after histolysis. In a number of places in the insect's body are collections of special formative cells which have played no part in the insects larval life and have stayed hidden or protected during this partial death. Each of these groups of cells is called an ‘imaginal disk' or a ‘histoblast'. The imaginal disks begin to reproduce rapidly and develop into wings or legs or antennae, from the largest structure to the most tiny detail of a single hair or scale, building a new body out of the soup that the insect’s digestive juices have made of the old larval body. This they do using the same biochemical processes that all insects use to turn their food into part of their bodies.
This rebuilding process is called ‘histogenesis' which is the formation of different tissues from undifferentiated cells. During this time the insect is very vulnerable because it cannot run away, and this is why insects try to choose somewhere safe to hide away when they are going through this incredible change.
For more information, check out this article written by Dr Lincoln Brower.

Caterpillar Anatomy: Senses and Defenses

Vision:
The caterpillar’s head contains the mouth parts along with eyes and antennae. Caterpillars have poor vision. Though many appear to have large eyes, these are actually false eyes designed to fool predators. (Click here to see great examples.) A caterpillar actually has six pairs of very simple eyes called ocelli, which provide a general picture of the world around it. Instead of using their eyes to find food, the caterpillar relies on its antennae, which once again can fool the casual observer.

Antennae,Tentacles, and Tubercles:
Most people assume the spiky projections they see sticking out from a caterpillar’s head are antennae. In fact, a caterpillar’s antennae are very short projections found close to the caterpillar’s mouth, as shown in the drawing above. Along with the maxillary palp, these small projections are used to find and identify food.

Many caterpillars also have one or more pairs of tentacles, which are also used as sensory organs. These fleshy tentacles are often found at the front and back ends of a caterpillar, but several more pairs may be found along a caterpillar’s body.

Some caterpillars also have tubercles along their bodies. These fleshy knobs are sometimes topped with spikes, providing a caterpillar with protection from predators. The Pipevine Swallowtail caterpillar (Battus philenor) to the right has both long tentacles and short, light-colored tubercles.

Setae:
In addition to tentacles and tubercles, caterpillars also have setae, short hairs covering all or a part of their bodies. These hairs are very sensitive to touch. They can also serve as a form of protection, as the setae can come off and irritate membranes around the eyes and mouth of an attacker. On the Gulf Fritillary (Agraulis vanillae) caterpillar to the left, notice the tubercles topped with black spikes. Each spike is further covered in tiny hairy setae.

Caterpillar Defenses:
Caterpillars are food for almost anything larger than themselves: birds, lizards, even wasps will prey on these creatures. Caterpillars have a variety of defenses, including camouflage, toxicity, and mimicry.

Camouflage allows caterpillars to blend into their surroundings. Sulphur caterpillars are often the exact color of the leaf they are eating, and they lie along the center of the leaf, blending into the mid-vein. Other caterpillars, such as the Long-Tailed Skipper (Urbanus proteus) shown to the right, roll leaves around themselves to hide as they eat.

Host plants can also help caterpillars by making them toxic to predators. Some caterpillars isolate toxins from the plants they eat, causing the predators who eat them to become sick or even die. Caterpillars in the swallowtail family use these toxins to coat their osmeterium, a fleshy organ that is extended from the head and emits a foul smelling liquid. (Click here to learn more.) Toxic caterpillars, including monarchs (Danaus plexippus), are often brightly colored to warn predators to stay away. This behavior is known as using aposematic signals.

Caterpillars use several types of mimicry for defense as well. If a caterpillar is not toxic itself, it may mimic aposematic signals to make predators think that it is. Caterpillars may also mimic less-appetizing objects to trick predators. Giant Swallowtail (Papilio cresphontes) caterpillars, shown to the left, are camouflaged not as leaves, but instead to resemble bird droppings.

Illustration Credit: Caterpillar Head Drawing via MonarchLab.org

Caterpillars and Silk

Caterpillars of both moths and butterflies have the ability to produce silk, much like a spider. They lose this capability once they transition to butterflies and moths, as it is no longer needed. As caterpillars, they use their silk in a variety of ways, some of which are truly startling.

How Caterpillars Produce Silk:
Like spiders, caterpillars produce silk through a “spinneret”. This tube-like structure is located on the lower side of the caterpillar’s mouth. Silk is generated as a liquid in the salivary glands and excreted through the spinneret; as it makes contact with air, it turns into a solid silk strand. Silk is one of the strongest natural fibers – it’s said that pound for pound, silk is stronger than steel.

A monarch caterpillar uses its spinneret to create silk.
Copyright © 2006 Hannah Nendick-Mason via BugGuide.net

How Caterpillars Use Silk:
Silk is important to caterpillars from the time they emerge from the egg to the time they enter their pupal state. Many kinds of caterpillars use a single strand of silk as a “safety line” to anchor them to the plant they are eating. If disturbed or dislodged, the caterpillar can drop down and hang from the silk line, almost seeming to rappel away from danger. When the danger has passed, the caterpillar draws the silk back in and makes its way back to the leaf to continue its meal.

Some caterpillars use silk to help create protective shelters. The “leaf-roller” caterpillars attach silk to both sides of a leaf and then draw the silk tight, pulling the leaf around them, as shown in the picture to the right of a canna skipper. This hides them from predators and creates a safe haven for dining in peace. Other silk shelters are more obvious, such as those created by tenting caterpillars. In that case, large groups of caterpillars create large protective “tents” of silk, in which all the caterpillars can live and eat in relative safety. (Learn more about tent caterpillars here.)

The most well-known use of caterpillar silk is, of course, in preparing to pupate. Moth caterpillars and butterfly caterpillars use the silk differently in this process. Moth caterpillars use silk extensively to spin a cocoon, a protective shelter in which they will shed their skin one final time and form a pupa. This process is especially obvious in the Silkmoth family, including the Polyphemus moths we raise here at BioWorks. These moth caterpillars spin hundreds of feet of unbroken silk, sometimes incorporating nearby leaves and twigs, in a process that can take hours or days. Click here to see time-lapse video of this process.

Butterfly caterpillars do not spin a protective cocoon. Instead, they use their spinnerets to create a small pad of silk to which they attach a hook at the end of their abdomen, known as a cremaster. Some caterpillars also produce a strand of silk about mid-way down their bodies, as an additional anchor to hold them in place while in chrysalis.

In the picture to the right, notice the Eastern Black Swallowtail caterpillar is attached at the end of the abdomen to the stick. (You can click the picture to enlarge it.) Though difficult to see, there is a pad of silk there. Note that the caterpillar has also slung a silken string around its midsection, holding it in place. The string remains even when the caterpillar pupates into chrysalis. If the tail end of the caterpillar should become detached, the center line will still be there to keep the chrysalis safe until the butterfly emerges.

One uncommon use of silk by caterpillars is for hunting. A select few caterpillars around the world are carnivores instead of herbivores, and use silk to catch their prey, much like spiders. One such species is Hyposmocoma molluscivora, a moth found in Hawaii. This caterpillar uses silk to trap snails, after which it climbs inside the shell, backs the snail into a corner, and eats it. Learn more about this unusual caterpillar here.

What About Silk Cloth?
Commercial silk is generally produced by the Domesticated Silkmoth caterpillar, Bombyx mori. This silkworm was domesticated thousands of years ago in Asia from the Wild Silkmoth, Bombyx mandarina.  B. mori does not live in the wild, and in fact could not survive in the wild because the adult moth is flightless. The caterpillars are raised in large factories where they are fed White Mulberry (Morus alba) leaves up to eight times a day. Once in cocoon, most of the pupae are not allowed to survive to adult moths, as they would destroy much of the silk when breaking out of the cocoon. The cocoons are generally boiled, which kills the caterpillar and loosens the silk for unwinding. To learn more about the process of producing silk commercially, click here.

Caterpillar Anatomy: Digestion, Respiration, and Locomotion

Though a caterpillar’s anatomy is somewhat simpler than that of a butterfly, there’s more to a caterpillar’s body than meets the eye. While much of the body is taken up by the digestive tract, appropriate for a creature whose main task in life is eating, a caterpillar’s body also needs to breathe, move, sense the world around it, and defend itself. (Note that caterpillars lack reproductive organs; mating takes place only as adult butterflies.) This week we’ll take a closer look at caterpillar anatomy; look for posts later this week on Caterpillars and Silk and Caterpillar Senses and Defenses.

 
Digestive Tract:
A caterpillar’s body is basically a long tube. The mouth, with mandibles for chewing, is at one end. The digestive tract runs the length of the body, ending in the anus, where the caterpillar excretes waste. (Learn more about caterpillar waste, called frass, by clicking here.)

This digestive tract is especially easy to see on the Canna Skipper caterpillar (Calpodes ethlius), as it is essentially transparent. The green color on the caterpillar to the right is actually the plant material inside its gut. As it travels through the gut, the caterpillar extracts the nutrients, expelling only that which it cannot use. Caterpillars are extremely efficient digesters.

Legs:
While caterpillars may appear to have many sets of legs, they actually only have six true legs, like all insects. The legs on the three segments of the thorax, toward the front of the body, are the true legs, jointed and ending in hooks. On the abdomen, the caterpillar has sets of prolegs, which are stumpy and end in sticky suction-cups called crochets. These prolegs allow the caterpillar to cling to surfaces even when upside-down.

In the photo of a Black Swallowtail (Papilio polyxenes) caterpillar to the left, note the true legs held close to the head, pulling the parsley stem close to the mouth. The prolegs are further down the body, clasping the stem.

Respiration:
Caterpillars also need to breathe. They take in air by means of spiracles, tiny holes along the sides of their bodies that deliver oxygen directly to their body tissues via tracheae, eliminating the need for lungs. Spiracles can be opened and closed to control water entering or exiting the body. Once again, spiracles and their web-like tracheae are easy to see on the transparent body of the Canna Skipper caterpillar below.

The Senses of Butterflies: Hearing

Some butterfly families have a specialized organ on their wings that works somewhat like an ear. This organ is a fluid filled sac covered with a thin membrane. High frequency sounds will cause the membrane to vibrate and send signals to the butterfly’s brain.

Some butterflies are even able to differentiate between high and low pitch sounds which may help them with locating other members of their species or to avoid predators. The wide veins at the base of the fore wings contain nerve cells similar to those found in the hearing organs. Some species have good enough hearing abilities that they will react to the crunch of leaves under your feet as you approach them or will take flight in response to the click of a camera shutter.

The first butterfly ear structures were discovered in 1912 but it is only in recent years that scientists have begun to study the physiology of these organs. The ear structure on a butterfly wing is known as a Vogel's organ. This structure is made up of a thin tympanum bordered by a ring of rigid chitin and the inner surface of the tympanum has several sensory organs.

Hamadryas: The genus Hamadryas, also known as Cracker Butterflies, are known to emit clicking sounds when they are disturbed. The Blue Cracker (Hamadryas feronia) of Venezuela emits shorts trains of clicks and also double click sounds.

Morphos: Research at the University of Bristol in England has focused on the study of wing ears of the Blue Morpho (Morpho peleides) butterfly. Scientists used a tiny laser beam to scan the surface of the tympanal membrane of the wing ear and determined that different areas of the membrane vibrated with different frequency sounds. Lower frequency sounds vibrated only an area on the outer membrane  while higher frequency sounds could vibrate the entire membrane. This means that not only can the butterflies hear sound, but they are likely able to distinguish between different sounds.

Heliconians: In 2004, a UF researcher named Mirian Hay-Roe noticed that the Blue & White Longwing (Heliconius cydno) butterflies that she was studying were making clicking noises. Observation showed that the butterflies made clicking sounds when chasing rivals out of their territory, encountering members of their own species, flying with members of their own species and also while roosting at night. Mirian Hay Roe recoded the clicking sounds of this species and recordings of the noise are available here.

Hedyloids: This superfamily of nocturnal butterflies is often known as the American moth-butterflies. This group of butterflies has been found to possess a Vogel’s organ on their wings that may help them detect and avoid bats, a predator of these nocturnal butterflies.

The Senses of Butterflies: Touch

Butterflies and other insects experience touch through hairs called tactile setae  that grow in flexible sockets much like a ball and socket joint. Beneath the exoskeleton, each tactile setae is attached to a nerve cell which will relay information about the movement of the setae to the brain of the butterfly.

Tactile setae can be found all over the body of the adult butterfly. The proboscis, legs, thorax, abdomen, head, and palpi are all covered in these tactile sensing hairs.

On the wings of an adult butterfly there are several groups of specialized setae and nerves. These groups of setae help the butterfly to sense gravity, wind, changes in  air pressure and the position of the wings. Other tactile setae detect the position of the butterfly’s head, legs, antennae and body.
Seta (plural setae) is derived from the Latin for ‘bristle’.

The Senses of Butterflies: Taste and Smell

Chemoreceptors: Specialized sensory nerve cells or sense organs that respond to chemical stimuli. Etymology: Gk, chemeia + L, recipere, to receive

Butterflies experience taste and smell in much the same way as humans, through the use of chemoreceptors on the body. In humans chemoreceptors can be found on our tongues in the form of taste buds and in specialized sensory cells found in our noses.

The sense of smell in butterflies is experience mainly through their antenna. Butterfly and moth antennae are covered in densely packed chemoreceptors. Depending upon the species of butterfly, these chemoreceptors are utilized to smell the pheromones of the opposite sex of their species so butterflies can find each other to mate. Chemoreceptors may also smell the honey scent of flower nectar and the scents of other food sources.

Tasting with your feet: The butterfly body is covered in chemoreceptors. On the butterfly tarsus (foot) contact chemoreceptors can sense the presence of dissolved sugars like those found in flower nectar. When the taste sensors are activated, the butterfly will uncoil its proboscis to consume the nectar it has detected. By just landing on a surface, a butterfly can taste if something to eat is available.

Female butterflies have specialized chemoreceptors to help them find the right host plant. Female butterflies have tiny spines on the backs of their legs that are used to drum against a plant leaf and release juices from the plant. These juices or the plant surfaces are tested or tasted by chemoreceptors at the bases of the tiny spines and can determine if the female butterfly has found the right host plant for her eggs. Some species of butterfly like the Monarch will test a host plant with all six legs before beginning to lay eggs.

What if you experienced taste through your feet? Here at BioWorks we often ask that question of visiting school children and receive a bunch of frowns and exclamations of “Yuck!” or “Gross!” in response. We often utilize that opportunity to suggest they keep their shoes clean.