THE NATURALIST’S NOTEBOOK: Moth hunting in Brazil
Exploring and identifying the treasures of a rainforest
David S. Rolnick
Phil Bader
This article is dedicated to my dear friend and mentor Nick Wagerik, who first introduced me to entomology and with whom I spent countless hours roaming New York’s Central Park in pursuit of dragonflies and moths. Nick passed away last week.
After I graduated from MIT, I took a few weeks off from math and dived into the Brazilian rainforest. One of my hobbies is photographing and identifying moths. It turned out that a field station near Rio needed someone to help photograph and identify the moths of a critically endangered ecosystem. MISTI Brazil stepped in to provide support for the project, and I flew to Rio.
There are about 160,000 species of moth known to science, a diversity only surpassed by the 400,000 species of beetle. To put that another way, one in every ten species of anything is a moth, even if you count bacteria and plants. Once you start looking, moths turn out to be as beautiful as they are diverse. It’s like being in a museum with 160,000 paintings. Even in the U.S., those tiny brown things that fly out of your cupboard are nothing to the myriad shapes and colors that you can find just by leaving a light on at night.
Over several years, I identified more than 500 species of moth at a single window of my family’s house in Vermont. My reference was the Moth Photographers Group, a fairly comprehensive online guide to the 12,000 species of U.S. moths. In Brazil, however, there aren’t any identification guides at all. To work out the identity of a moth you have to look laboriously through museum collections or hope that there are photos online. It’s much more work, but it’s also more exciting.
Brazil’s Atlantic Forest is less well known than the Amazon, perhaps because 93 percent of it is gone. It once stretched along the entire eastern coast, but now, like the northeastern seaboard of the U.S., it’s become mostly farms and cities. The few remaining fragments of rainforest are home to an outstanding array of species found nowhere else.
The Reserva Ecológica de Guapiaçu (REGUA) protects one of these fragments. Trails wind up through the jungle into a ridge of high mountains as improbably emerald as Oz. There are research facilities, observation towers, and volunteers planting native trees. There is also a tourist lodge, where birdwatchers from all over the world flock to see such local rarities as the Shrike-like Cotinga and the Giant Snipe.
The station used to be a ranch, like most of the neighboring land, but a lab and a ping-pong table have now replaced the cows; visiting scientists get to stay in bedrooms instead of a chicken coop. The buildings are surrounded by fruit trees, including one big cashew tree just outside the kitchen, which is always filled with very cute monkeys called tamarins. It turns out that in the U.S., we miss out on the best part of the cashew, which is the juicy fruit that surrounds the nut. I learned a lot about fruits in Brazil. I had my first experience chopping down a bunch of bananas with a machete, and I learned how to distinguish wild limes, which look exactly like oranges, from wild oranges, which also look exactly like oranges. There is nothing quite so sour as a wild lime.
The forest is brimming with wildlife. The field station sits beside a large wetland filled with birds like the Purple Gallinule and Whistling Heron, as well as capybara, which are pig-sized rodents with hair like a coconut. As I carried my UV moth light along the path at dusk, I would inevitably hear a horrifying hoarse scream, followed by a loud splash, as a dozen frightened capybara leapt into the water with the agility of large stones.
Returning from a walk one day, I heard the forest rustling around me and noticed that I was in the middle of a swarm of army ants. There was a gigantic fig tree nearby with roots as tall as I was. In between two of these roots, the ants were building a nest out of their bodies to shelter the queen and the young. Since a swarm eats so much every day, it is constantly on the move, so the only way they can have a house is if they make the house themselves. I estimated this one held about five gallons of solid ants.
There are also snakes, which one imagines are hiding everywhere (and probably are). One evening I went out camping with the other visitors and, after drinking some caipirinhas made with the wild limes, we decided to play hide and seek in the pitch-black forest. Having discovered that nobody could find anyone else in the undergrowth, even with flashlights, we went to bed. Next morning, we found a highly poisonous viper curled up on the ground just where we’d been playing.
Then there are the moths. There is the Yellow Furry-Legs (genus Acraga), which is yellow and has furry legs. There is the blue-spangled Hypocrita bicolora and the tiger moth Leucotmenis nexa, like an iridescent green wasp. Giant silkmoths sit on the ground and appear to be dead leaves until they reveal bright orange hindwings with giant blue eyespots.
The White Witch (Thysania agrippina) looks like a calligrapher’s notebook, and is the largest moth in the world, with a 12-inch wingspan. Its somber brown cousin, the Black Witch (Ascalapha odorata), is traditionally believed to be a harbinger of death. REGUA is also home to the second scariest moth in the world (after the Vampire Moth of Malaysia). This is the Assassin Caterpillar (Lonomia obliqua), which camouflages itself against tree trunks and injects a potent neurotoxin into anyone who accidentally touches it.
Every night, I set up lights and ran around trying to find and photograph as many species as possible. During the day, I compiled my own photos and those of other scientists at the reserve, and worked on the monumental task of identifying species. Through an online database, entomologists affiliated with REGUA can now post and identify photos, and our list of species has grown dramatically. We have yet to discover a species entirely new to science, but 150 identifications is a good start.
In those three weeks in Brazil, I learned a lot. I discovered a country and a culture that I loved. Brazilians seem never to stress about anything, and enjoy life no matter what. I also got much better at dealing with new kinds of problems. At one point, for instance, a rather rare species of owl wandered into the lab and flew around in a panic, knocking things over and even perching on my shoulder in its confusion. We ended up catching the owl in a box and releasing it outside.
I’ve found that however much I may love reading papers, working on problem sets, and puzzling over elegant research questions, I still need, sometimes, to get out to a forest. I’ve just returned to MIT to begin my PhD in Applied Math. My thoughts and plans are full of graph theory and algebraic geometry. But I’m talking to MISTI about spending some of my IAP in Brazil. There are still so many moths out there to discover.