Both species featured in last week’s “What Is It!” were observed in eastern Massachusetts during early autumn. The plant image, submitted by Karen, was photographed in the town of Harvard on September 29. Let’s look closely at her photo to gather the details that will identify it.
Entire Plant, Harvard, MA
Her original image displays a white-flowering plant that is growing in a deciduous forest with filtered light. Its leaves have conspicuous teeth, and its flowers grow in flat clusters. When we zoom in, a few more details become apparent.
Closeup of One Inflorescence
The plant’s somewhat heart-shaped leaves are arranged opposite to one another. They are attached to the stem by long stalks called petioles.
If we push the magnification even further, the individual flower heads appear to be “all middle” with no petals. This is what is known as a disk flower. Imagine a daisy without petals. Disk flowers (and combinations of disk and ray flowers) are typical of the aster family. From a distance, these flower parts appear to be “indistinguishable.” If we could examine the details with a hand lens, we would see that each flower head is actually composed of tiny florets. Some of the reproductive parts protrude, thereby giving the flower a fuzzy appearance.
Karen’s Plant, Disk Flowers
Ageratina altissima, Onondaga County, NY
R. A. Nonenmacher, CC BY-SA 4.0
This combination of details and a good key such as Newcomb’s or GoBotany will lead you straight to an identification: white snakeroot. Native to much of eastern North America, white snakeroot is one of the last wildflowers to bloom in fall. Its late-season flowers provide nectar for a wide range of insects including bees, wasps, flies, butterflies, and moths. Better leave this plant to its insect partners, though, for it contains a toxin that can poison livestock who graze on it and the humans who consume their meat or milk. During the 19th century, new settlers to the midwest suffered from a mysterious illness that they called “milk sickness.” Many died before the connection to white snakeroot was discovered. See “The Plant that Killed Abraham Lincoln’s Mother” for a neat summary.
Although the snakeroot won’t cure snake bites or fill our tummies, its brilliant white flowers do provide an ethereal beauty to autumn strolls.
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Our second “What Is It!” crawled through my Pembroke yard on September 26. I was searching for spiders near the house foundation when I spotted this impressive caterpillar nearby. It was large – perhaps 2.5 inches – handsome, and covered with short, stiff hairs. The Peterson First Guide to Caterpillars of North America describes such caterpillars as “bristled” and says that they belong to the tiger moth family.
From a distance at least, the insect appeared to be solid black. My position, teetering on muddy stairs beneath a large mock orange shrub, didn’t allow for close inspection. If I had been able to give the creature a gentle poke, it would have curled into a defensive ball, perhaps allowing me to see the diagnostic crimson bands between its segments or its orange/red spiracles (openings to respiratory system). This is what I missed:
Hypercompe scribonia found in southern NJ in November
This species of tiger moth is actually a leopard, a giant leopard moth caterpillar. Like other tiger moth caterpillars, it is a generalist, feeding upon low-growing plants such as plantain, dandelions, and violets as well as some trees and shrubs. Those bristles (called setae) help protect the caterpillar from predators though, by most accounts, they are not poisonous. This species overwinters as a caterpillar and pupates in the spring. It is most conspicuous in autumn when it moves from its feeding grounds to shelter beneath tree bark, under plant debris, or perhaps, in your garage. According to BugLady of the University of Wisconsin, these overwintering larvae produce a chemical “antifreeze” to help them survive the cold.
Many of these characteristics will likely bring to mind another caterpillar, the banded wooly bear. Here is one crawling on the library’s footbridge last October
This is, perhaps, the best-known caterpillar in our area. Like the giant leopard moth, it is covered in bristles. It, too, feeds on low-growing plants, is observed crossing roads, rolls up when disturbed, and overwinters as a larva. Most individual caterpillars have black and rust-colored bands the width of which, according to folklore, forecast the severity of the approaching winter. My specimen is more rust than black which could mean 1) a mild winter 2) a more mature caterpillar 3) a caterpillar that grew up in dry conditions or 4) you name it! As BugLady notes, there is much speculation in this matter. Entomologist Michael Raupp provides a little historical background and humor in his Bug of the Week column.
Several other fuzzy caterpillars are nicknamed woolly bears. A few of these tiger moth larvae are described in Bug Bytes, a publication of Ohio State University.
I should note that “banded woolly bear” is the name of that animal’s larva. The adult form is the Isabella tiger moth, an insect with rather dull yellow wings and some spotting. To my mind, the adult giant leopard moth is a strikingly beautiful creature: pure white with black rings and spots. Though I have seen these beauties, I don’t have a photo to share. Enjoy this Wikipedia image until you see one for yourself.
Jeremy Johnson, CC BY-SA 4.0
Better yet, reserve a copy of Caterpillars of Eastern North America by David Wagner, a rich-but-accessible guide that includes full-page accounts of hundreds of species, images of larvae and adults, distribution, food plants, life history and more. This book is also available through Hoopla.