Invisible Nature: Invasion of the Caterpillars

Gypsy moths have been gaining ground in North American forests for 150 years. Can a caterpillar-melting virus keep them in check?

In the 1860s, artist and amateur scientist Leopold Trouvelot hatched an ill-conceived plan to create a new type of silk—a plan that included importing gypsy moth caterpillars (Lymantria dispar) from France to America. Instead of a better textile, Trouvelot created an ecological disaster. When some of his caterpillars escaped into the surrounding Massachusetts countryside, they thrived. Free from many of their native predators, they stripped trees bare as they munched their way across an ever-expanding territory. Nearly 150 years later, gypsy moth populations are still spreading, causing significant damage to deciduous forests wherever they go. (This past summer, caterpillar-induced defoliation was so extensive across New England and the Mid-Atlantic states that it could be seen from space.) But there’s hope for the trees. A virus that causes the caterpillars to melt into piles of goo is helping to keep the gypsy moth in check—and limiting its impact on countless U.S. forests.

Annette Heist, Ruth Lichtman, and Flora Lichtman

Annette Heist is a science writer, radio producer, and a registered nurse working in behavioral health. Ruth Lichtman is a multi-disciplinary visual artist and filmmaker whose work has been featured on The New York Times, The Atlantic, Aeon, and The Huffington Post. Flora Lichtman is a science journalist who has worked for “Bill Nye Saves the World” on Netflix, The New York Times, and Science Friday. She hosts a podcast called Every Little Thing.

bioGraphic is powered by the California Academy of Sciences, a renowned scientific and educational institution dedicated to regenerating the natural world through science, learning, and collaboration.