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October Species Spotlight: Isabella Tiger Moth (aka the Banded Wooly Bear Caterpillar) and the Spotted Lanternfly
October 14, 2021
Indigenous Species:
Pyrrharctica isabella, the Isabella Tiger Moth, aka the Banded Wooly Bear Caterpillar
(c) arianeg, some rights reserved (CC BY-NC-ND)
This month we feature a species local to our area that many people hiking the Wallkill Valley Rail Trail or Joppenbergh Mountain can identify, the Banded Wooly Bear Caterpillar. (Many species are known as “wooly bears”, but this specific one is the only species to sport an orange band.) As the weather gets colder, it’s fairly common to see these fuzzy black and orange caterpillars scurrying around. The ones we spot at this time of October are the second generation of the year, having hatched from eggs laid sometime in August. The lesser-known adult version of this caterpillar is the Isabella Tiger Moth, a yellowish-gold moth with about a 2-inch wingspan.
The first generation of the year hatches in May, and spends the summer chowing down on leafy greens. Unlike some specialist caterpillar species that only prefer one kind of plant to eat (such as the monarch caterpillar’s love of milkweed) the banded wooly bear is a generalist, and will eat just about any plant in its path that isn’t woody and tough. If you find one in your garden and you’d prefer it didn’t eat the flowers you’re tending, you can simply relocate it to a wild plant elsewhere. The adults drink nectar, so it’s handy to have them around as helpful pollinators!
Wooly Bear by Robin Kuehn
Some people believe that the bands on wooly bear caterpillars can help us predict how severe the upcoming winter might be. This hasn’t been proven to be correlated; instead, the caterpillars usually gain more orange hairs as they mature, so a mostly black caterpillar with a narrow orange band will likely be younger than a mostly orange one.
Our October wooly bears don’t have time to pupate and grow into adult moths before winter, so they have an amazing strategy to survive the cold. They find a nice protected spot under some leaves or bark, and when the ground freezes, they freeze solid too! Wooly bear caterpillars are able to make substances called glycoproteins, which is chemically very similar to the antifreeze in your car. It allows them to keep ice crystals from forming randomly in their cells – when this happens in species of plants and animals that don’t have the glycoproteins, the crystals completely shred the cells, sort of like that lettuce you accidentally put too far back in the fridge and thawed into a pile of mush. The glycoproteins prevent the water in their cells from meeting nucleation sites where the ice crystals would form, allowing them to become supercooled. Once the ground reaches a certain temperature, though, they flash-freeze! This way they freeze solid instead of having little bits of frost appear throughout their bodies, and they are protected from both the sharp crystals and from constantly freezing and thawing as the temperatures fluctuate. When the spring warms them up enough to completely thaw, they continue about their business finding food.
If you want to see more of these intrepid little survivors in your yard, be sure to “leaf” them some habitat! Wooly bear caterpillars depend on undisturbed plant waste such as leaf litter, rotting logs, and dead flower stems to overwinter, as do many other helpful insects such as Bumblebee queens and the caterpillars of Luna Moths and Great Spangled Fritillaries. You can ditch the rake this year and leave the leaves for wildlife, and simply mulch the leaves into your lawn in the spring. If you must have your lawn leaf-free, consider raking the leaves into your flower beds to help insulate the plants and to help out some little but amazing local wildlife.
Colonizing Species, Revisited:
Lycorma delicatula, The Spotted Lanternfly
Spotted Lanternfly C. Lawrence Barringer Pennsylvania Department of Agriculture bugwood.org
Our avid Field Notes readers know we already covered the Spotted Lanternfly in October 2020; for a recap, check out that article, written by our fabulous intern Kaitlyn Skees.
We decided to mention them again, since they pose a significant threat to the apple, hops and grape crops so many of us enjoy as part of an iconic Ulster County autumn. First spotted in Pennsylvania in 2014, these colorful insects made it to Staten Island in 2020, and have now been confirmed to have spread as far across our region as Ithaca in Tompkins County, and Worcester County in Massachusetts.
The DEC is looking for survey volunteers to track the Spotted Lanternfly and help protect New York’s iconic farms and forests. You can register and learn more here: https://www.nyimapinvasives.org/slf
The DEC also has encouraged anyone who may come across these insects to help us stop the spread. Yes, squishing them will stop at least that individual, but you can help researchers track the movement of the population by reporting all spotted lanternfly sightings to the DEC with the survey linked here, or by snapping a photo and posting it to iMapInvasives, or iNaturalist.
On iMapInvasives, you can register for free training webinars on how to identify and report the Spotted Lanternfly and its preferred tree host, the Tree of Heaven. There’s an upcoming free training on October 27, register here: https://www.nyimapinvasives.org/training
For more information about joining iNaturalist, and the global community of almost 2 million nature observers, check out our article from last June.
Thank you to everyone who already helps us steward these beautiful lands, our volunteers who help us manage colonizing species, and our generous supporters who make our work possible.
Banded Wooly Bear Resources:
http://jeb.biologists.org/content/jexbio/early/2015/12/04/jeb.124875.full.pdf
https://ipm.missouri.edu/MEG/2014/11/Wintery-Weather-Folklore/
https://nystateparks.blog/2015/09/29/the-folklore-of-the-woolly-bear/