Talking Caterpillars
Since creating a large home garden, I have become reacquainted with these guys and plenty of other garden denizens. Enjoy.
In the Field | David L. Wagner
Quick, Before It Molts
A recent sweep of a Connecticut state park by David L. Wagner and others produced a variety of caterpillars, including this early version of the monarch butterfly. More Photos >
EAST HAMPTON, Conn. — David L. Wagner was beating the bushes in a state park here the other day, hoping to flush out new kinds of caterpillars, when a colleague walked over and presented for inspection a plump, milky-green creature he had just found crawling on a leaf. The caterpillar was not particularly rare, but Dr. Wagner set down his stick to greet an old friend.
David L. Wagner, author of “Caterpillars of Eastern North America,” says the world owes them a debt. More Photos »
A generator provided the power, a light provided the lure in a search for caterpillars. More Photos >
“Abbot’s sphinx!” he called out. “One of our only talking insects.”
He trained his ever-present field magnifier on the bug’s back, which sprouted a cadmium-yellow horn-shaped protuberance. After the next molt, Dr. Wagner said, “the horn turns into an eyelike button — it actually looks like your eye — and if you touch the eye the caterpillar reels around and squeaks like a mouse. Scares the bejesus out of you, is what it does.”
Dr. Wagner went back to whacking at grass stalks with renewed vigor. “You don’t need to go to the Amazon,” he said. “You don’t need to go to New Guinea. You go out your back door with a hand lens and you’ll find some pretty amazing things that a lot of people have overlooked.”
More than 600 of those things populate the pages of “Caterpillars of Eastern North America” (Princeton University Press, 2005), a lusciously photographed book generally regarded as the most comprehensive field guide ever to caterpillars, as opposed to their better-documented adult forms — moths and butterflies.
In the book, the fruit of a decade’s research, Dr. Wagner, an associate professor of ecology at the University of Connecticut, argues passionately that creeping things can be every bit as mesmerizing and transporting as those that flit and dart in the air.
Take, for instance, the camouflaged looper, an inchworm that cloaks itself in shredded bits of the flower it is feeding on. “A Mardi Gras caterpillar that is out of costume only after a molt,” Dr. Wagner writes. Or the orange dog, scion of the handsome but rather mundane-looking giant swallowtail butterfly. The orange dog looks like a squirt of fresh bird droppings with two long retractable magenta fangs; as the book notes approvingly, “a caterpillar with excellent options in both bird-dropping and snake-mimicry.”
The names alone — abrupt brother, horrid zale, curved-lined angle, grapeleaf skeletonizer, monkey slug — make the book absorbing reading.
Though Dr. Wagner has observed more than 1,000 species in his backyard in Storrs, in northeastern Connecticut, he found much to interest him here at Hurd State Park, less than 30 miles south.
At the edge of a grassland by the Connecticut River, he examined his beating sheet, a white nylon kite stretched across a wood frame, and picked up a beige, wormy-looking caterpillar with dark brown streaks running along its back. “I don’t think I’ve seen that one before,” he said.
In just the past year, Dr. Wagner has discovered and described a half-dozen species that had either never been observed in their caterpillar state or were new to science altogether — a fact that says much about the primitive state of caterpillar studies.
“Caterpillars are the last unknown group of big things on the terrestrial world,” said Daniel H. Janzen, an ecologist at the University of Pennsylvania who has studied the caterpillars of one corner of Costa Rica for 25 years.
“You step off a plane in some place like Venezuela and walk out into the forest, pick up a fruit or a skull or a butterfly or a bird — anything big enough to hold in your hand — it’s got a name, and there is someone who can tell you what it is,” he said. “That’s not true for caterpillars, the world around.”
There are several reasons. Few reference-quality collections of specimens exist, because, unlike birds and beetles and butterflies, dead caterpillars do not keep well. Scientists have tried pickling them in alcohol, or hollowing them out and blowing them up like little balloons, but both techniques distort them badly.
And until recent advances in DNA science, the only way to identify a caterpillar positively was to rear it to adulthood, which requires careful husbandry. (There are well-known moths whose caterpillars have never been seen by science.) Most caterpillars shed their skins five or six times as they grow, and each stage, or instar, can have radically different markings and patterns from the previous one.
“In order to do this well, you sort of had to know the entire universe,” said Dr. Wagner, who said that 5 percent to 10 percent of the caterpillars in his book had never before been studied through their entire life cycles. The 700 species in the book are only a small fraction of the 5,000 east of the Mississippi.
Dr. Wagner, a tall 49-year-old Californian whose trim mustache and lantern jaw lend him an air of the safari, started out as a botanist but was drawn to insects and then caterpillars by luck and circumstance.
In 1992, for research on how a common bio-organic pesticide used against gypsy moth caterpillars affected other species, he and his team collected 12,000 caterpillars in a Virginia forest and reared them to adulthood. The data yielded a guide to 50 common forest caterpillars. The federal Forest Service printed 5,000 copies, which were snapped up in a few months.
“At that point we knew we had something special, and that there was this enormous void,” Dr. Wagner said. His current book, “Caterpillars of Eastern North America,” has gone through three printings and has sold more than 10,000 copies.
Caterpillars are in some ways ideal subjects for the amateur naturalist. They do not fly or run away when someone tries to look at them, they can be found just about anywhere, especially in late spring and late summer, if you take the time, and even the most pedestrian-looking species reveal a visual riot of stripes and spines and spots and bumps with the aid of a 10-power magnifying hand lens. The all-too-common and destructive Eastern tent caterpillar is, on close inspection, a strange and striking insect, “lavishly variegated in steel blue, black, orange and white,” Dr. Wagner writes.
And unlike butterflies, caterpillars seem well suited to life in captivity. “When you capture a butterfly,” he said, “you’re interrupting the cycle of nature. When you capture a caterpillar, you’re probably saving its life, assuming you know what you’re doing.” Fewer than 1 percent of caterpillar eggs survive to adulthood in the wild.
Dr. Wagner said caterpillars also deserved appreciation for their indirect benefits to the world. They are a dietary mainstay of beloved songbirds, and it is to defend themselves against caterpillars that plants have developed many of mankind’s favorite chemical compounds, including nicotine, caffeine and tannins.
“When somebody tips back a glass of wine, they should be thanking caterpillars,” Dr. Wagner said. “You should be raising a toast.”
Dr. Wagner serves on the rare species advisory panel of the Connecticut Department of Environmental Protection, where his expertise gives him a strong voice in land-use decisions.
“I can set a trap anywhere in the state and, because I know the insects’ biologies, can tell you the next morning if that piece of land should be preserved, or else say ‘No, build a golf course here; we’ve got bigger fish to fry somewhere else,’ ” he said.
New specimens come to Dr. Wagner in all sorts of ways. After the foray in Hurd State Park, he met a state biologist in a restaurant parking lot near Wesleyan University in Middletown, Conn. The man handed off a vial containing a lime green, trilobite-like caterpillar with yellow chevrons on its back.
“I’ve never seen one of these alive before,” Dr. Wagner said. “I’ll get a great photo of him.”
After dinner, Dr. Wagner returned to the park with a class of Wesleyan students for a night hunt. They strung up lights and a sheet in a clearing.
Within minutes, the sheet was covered with moths — about 50 species, Dr. Wagner guessed. He pointed out a small dark-brown mothlike insect with a notched wing.
“This is really cool!” he said, explaining that its larvae live in termite nests and spray a paralyzing gas from their rears to immobilize the termites before eating them.
The students fanned out across the field with flashlights, looking for night-feeding caterpillars in the tall grass. One of them brought back a vial containing a chunky brown inchworm with a sleek face mask and four black dots on its back.
Dr. Wagner trained his lens on it. “I’m not sure what that is,” he said. “I’m interested in this one. If I could keep it, that would be great.”
He slipped the vial into his pocket.
Story #2
For Larvae Lovers, a Field Guide Online
By TINA KELLEY
ONSIDER the elusive caterpillar. It changes shape up to 12 times between the pupal stage and butterflyhood. It cannot be preserved well, as it loses all of its colorful glamour if dried, and it doesn't fare much better if boiled and stored in alcohol. With its thousands of varieties, fake eyes, stinging spines and occasional convincing imitations of bird droppings, it can be sphinxlike. Hazardous. And hard to get one's arms and mind around.
Recently entomologists have found the World Wide Web to be a durable, flexible and handy repository of information about caterpillars, better than a museum and preferable to books as a storehouse for data (if only the tenure committees agreed). A variety of sites provide rich information about caterpillars in areas like Australia, Costa Rica and the Pacific Northwest.
"Everybody can access it for free, you can continually update it, you can always improve it, and you can correct mistakes," said Lee Dyer, an assistant professor in ecology and evolutionary biology at Tulane University, who was dissuaded from publishing a book on Costa Rican caterpillars by Daniel Janzen, a professor of biology at the University of Pennsylvania. Dr. Janzen (with his wife, Winnie Hallwachs) maintains an extensive caterpillar site at janzen.sas.upenn.edu.
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The language of the scientist, as witnessed at Dr. Dyer's Web site, sometimes verges on poetry. The Nessaea aglauris has small bumps "covered in a diaphanous pearl color (silvery blue/white)." Some caterpillars have "gregarious" larvae, while a member of the Hesperiidae family is described as "body transparent but green because of gut contents." This particular invertebrate "thrashes/ bites and spits when disturbed." You can also read about the Adelpha celerio, which resemble moss or lichen-covered twigs. The site also lists unofficial common names of some caterpillars, including the Backflip barfer, Cherry-headed velvet and Fleshy crested wart butt.
Dr. Janzen, 63, said that his collection of pictures of caterpillars "simply isn't transmittable except by using the Internet." His site is an electronic field guide with 160,000 records and 20,000 to 30,000 pictures of caterpillars. "For this type of thing, books are completely obsolete," he said.
He enjoys being able to post a variety of photographs of each species from different angles at different stages of development. "How many juvenile cardinals do you see featured in a field guide?" he said. "And how many times do you see, in a field guide, a bird looking straight up, seen from the bottom, which is how I seem to see them, looking up from the bottom of the tree? You can't afford to do that in hard copy."
The detailed records that he and his wife keep of each butterfly collected in the forest that they study in Costa Rica could be useful for other scientists, and the Internet lends them a little more permanence.
"Traditionally, a database would sit in notebooks on my desk, and when I die it would be shoveled into a trash basket, but because it's on the Web, when I get run over by a truck, the data is still there," he said.
In the past, he said, scientists had to peruse their predecessors' work in scrawled entries in ancient field notebooks in rare-book collections.
Dr. Janzen estimates that fewer than 10 percent of the people using his site are academics. "The great great bulk are naturalists, moth and butterfly rearers, school kids, high school kids and artists," he said.
About half of his Web-related correspondence comes from nonacademic Internet surfers, he added. "I think most people are fascinated by the process of metamorphosis and think caterpillars are cute," he said.
The introduction to his site suggests that any commercial gains resulting from the use of the posted information be shared with the Área de Conservación Guanacaste in Costa Rica, where he does his research. Without such protected lands, he writes, "there is a significant chance that we will finish the 21st century with databases like these being the only record of what once was."###
posted by Joe Paris @ Tuesday, August 08, 2006
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