Venomous Caterpillars Inch Their Way into the Hudson Valley
Spring Brings the Hickory Tussock Moth Out of its Cocoon
Inching along the earth and plant undergrowth is a white and black fuzzy caterpillar, which looks seemingly innocent to the human eye. But that perception quickly falls away when a rash appears after attempting to hold or touch the cute critter. These little guys, known as the Hickory Tussock Moth caterpillar (Lophocmpa caryae), are commonly found inching along the Northeast during the fall and forming their cocoons in the winter. Not until late spring or early summer do these cocoons burst open and an adult moth emerges for the summertime.
On the caterpillar, white setae (or hairs) poke out from the white body, which is speckled with black spots. These features define the venomous caterpillars, which can reach up to 1.7 inches in size. Once these caterpillars emerge from their cocoons, however, they are light brown with assorted off-white-colored spots that match the color of their underwingers.
These critters are venomous, but not poisonous. A reaction to these caterpillars is similar to having touched poison ivy. In severe situations, someone may even have trouble breathing and with the need to throw up—but that is uncommon.
"It has what we call ‘urticating hairs.’ So if you rub against the caterpillar, you'll drag some of these hairs into your skin," said Dr. Timothy McCabe, an entomologist at the New York State Museum. “It’s safe to just brush off the bug with a twig.”
The caterpillar is considered venomous when the hairs are touched, which then can stick to the skin and inject its chemicals. These caterpillars are not poisonous, but are venomous. “This particular caterpillar tends to get a bad rap. This stems from irritants on the caterpillar’s white hairs which, in rare cases, cause allergic reactions when they come in contact with human skin,” said Jace Porter, invertebrate rearing specialist and outreach educator from The Caterpillar Lab in New Hampshire. “Sometimes, people who touch the caterpillars develop slight redness on their skin and, less frequently, an itchy, burning rash.”
In 2017, these critters were seen in Albany, Ulster, Orange and the Catskills when the moths in the summer layed a mass amount of eggs. But since then, they seemed not to be as great of a concern. Nearing the end of April, it would be expected for people to see the cocoons of these caterpillars before they turn into moths—which also have a similar poisonous reaction if touched.
“In the larval stage, Hickory Tussock moths are active in the daytime and are found in and near deciduous woods. The caterpillars primarily feed on the leaves of nut trees, such as hickory and walnut, but they will also eat a variety of other tree leaves such as ash, oak, willow, apple and elm,” said Emma Perry, an environmental stewardship technician. “The defoliation caused by leaf feeding is natural and does not cause mortality to host trees. In the early stages of larval growth, tree leaves are left ‘skeletonized’ by groups of about 100 feeding larvae.”
Some other plants that host these venomous critters include various trees like ash, elm, oak and maple. Their food habits are similar to those of more harmless caterpillars, including flower petals, stems, roots, grasses and foliage of some hardwood trees.
“These are totally native ... they feed birds, they keep plants in check, they feed other insects,” said Samuel Jaffe, naturalist and founder of The Caterpillar Lab. “They’re just an important part of our local ecosystem.”