Mysterious Moths

A small group of students settled into a circle of chairs and tables in the Great Hall. Tall windows let in the gray light of a passing rain shower and the deep green of hemlock trees. A white screen sat in front of the unlit fireplace, and as the projector bulb warmed up, the first image from Kyle’s slideshow came into focus.

Bright orange lichens caught my eye first. And then white lichens with black circles, all clinging to a forked stick. As I studied the photo, the big patch of dusty green lichen sprouted long, thin antennae, a hairy body, and shimmering green, black, and white scales on their wings. The lichen was, in fact, a moth!

There are quite a few species of lichen-mimic moths, explained Kyle Johnson, entomologist with the Minnesota Biological Survey and instructor for this two-day “Mysterious Moths” workshop held at the Forest Lodge Estate near Cable, WI.

“How many kinds of moths do you think there are in Wisconsin?” Kyle asked, and we went into game show mode, throwing out numbers while trying not to overshoot. “Two hundred!” was the first guess. Then eight hundred. Kyle waited. Finally, Jan Sharp, a volunteer who works with our museum collections went big: “Three thousand?” she offered, feeling a bit outrageous.

“Well, I personally have catalogued over two thousand moth species in Wisconsin, and many species are still unknown to science, so three thousand is probably about right!” said Kyle. He shared a map of his field sites with locations marked from the southern tip of Texas to the northern tip of Alaska, with Minnesota, Wisconsin and Michigan at the center. His next big trip will take him to the Yukon! Our jaws dropped at both the number of moth species, and Kyle’s impressive efforts to both catch and identify them.

Moth abundance is even greater than their biodiversity. In any given ecosystem – even the African savannah – insects are the dominant herbivores. They eat more plants than white-tailed deer or even a herd of wildebeests. And moths (in their larval form, caterpillars) are a big part of that feast.

Many kinds of caterpillars need specific host plants to survive. Monarchs and milkweed are the most well-known example. But for numerous micromoths, Kyle indicated that they were “fern feeders.” By that, he means that the caterpillars burrow into the stem of a fern and munch on the green soup inside. This time of year, if you notice a fern turning yellow when all of their neighbors are still green, chances are that there’s a caterpillar in the stem!

When we went out for a walk later that afternoon, Kyle swiped his net through a pine tree and found several little pine-feeding caterpillars who looked just like the needles, white stripe down the center and all. We discovered other moth larvae feeding between the layers of a common plantain leaf. These are just a tiny fraction of the herbivorous caterpillars in the woods and fields right now who are munching away. They, in turn, feed birds and bats, and many members of the food web.

Pine-feeding caterpillar.

On the pine tree are caterpillars, and on the moth’s family tree there are three main branches. One branch is composed of brightly colored, day-flying moths with slender bodies and little clubs at the tip of their antennae. Sound familiar? We call these butterflies! According to entomologists, butterflies are simply a small group of moths.

Macro and micromoths are the other branches on that tree. Macromoths are more evolutionarily advanced, and are often bigger and showier, too, while micromoths tend to be smaller and more primitive.

But not necessarily less beautiful. As Kyle clicked through his slideshow, we oohed and aahed at the fairy-like form of a micromoth. Their forewings were covered in a pattern of shimmering gold and turquoise scales. Their hind wings were a lovely mauve color with a delicate pattern of veins just barely visible. And all were edged with long, shimmering silver fringes.

“All butterflies and moths have fringes on their wings,” said Kyle, it’s just a question of size.” He explained that the smaller you get, the more that air behaves like a fluid. The fringes both add to wing area and reduce turbulence making it easier to fly. The fringes on monarch butterfly wings are almost invisible. For many micromoths, fringes are the main event.

The main event of the moth workshop came after dark. Kyle hung a white sheet with a mercury vapor lamp across an old driveway. Then he painted fermented banana goo onto the trunks of trees along the drive. Until almost midnight, our little group walked from tree to tree to the sheet and back, with stops at patches of blooming milkweed in between.

From drab lichen mimics to shimmering green wings; micromoths smaller than a grain of rice to underwing moths the size of my palm; we were captivated by the multitudes of mysterious moths.

Underwing Moth

Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is available to purchase at www.cablemuseum.org/books and at your local independent bookstore, too.

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. The Museum is open with our brand-new exhibit: “Anaamaagon: Under the Snow.” Our Fall Calendar is open for registration! Follow us on Facebook, Instagram, YouTube, and cablemuseum.org to see what we are up to.