(Nittany) Lions, (Isabella) Tigers, and (Woolly) Bears, Oh My!

Have you ever pondered the connection between folklore, the natural world, and science? Join Lisa and Pam as they unravel the mystery surrounding the woolly bear caterpillar and its legendary ability to forecast the severity of winter. Special guest  Dr. Jon Nese helps dissect this intriguing tale and provides insights into other natural weather predictors. We'll explore the importance of fallen leaves in protecting and nourishing pollinators, giving you a whole new perspective on your autumn walks.

Transcript

Lisa: 0:06

Hello everyone and welcome to Pollinator Confidential, a podcast featuring the untold stories of native plants and the pollinators who love them.

Pam: 0:17

I'm Lisa Schneider and I'm Pam Ford, and we are Penn State Extension Master Gardeners from the Snetsinger Butterfly Garden Habitat Project located in Tudek Park in State College, PA. At the SBG, we're all about the stories, tales of those fascinating interactions between plants, pollinators and people.

Lisa: 0:42

In our last episode we learned about monarch butterflies and their migration to Mexico, but you know, most pollinators don't migrate. It's a fairly uncommon strategy for winter survival. Today we'll be talking about how most pollinators spend the winter right here with us under leaf litter, and why fallen leaves are so important. But first we're going to take a closer look at a piece of folklore that's on a lot of people's minds at this time of year the woolly bear caterpillar.

Pam: 1:16

You know, at this time of year when the temperature is getting chilly and the leaves are turning, I like to make sure I always get out and take a good long walk, and if you're walking out at the Snetsinger Butterfly Garden, sometimes you'll see these caterpillars crossing the path right in front of you.

Lisa: 1:34

Now you all know the story, how the size of the rusty band on the caterpillar tells us how hard the winter is going to be, and I think a lot of people might have trouble remembering. Is it more black? That means a hard winter, or more orange, or what is it? But we're going to shed some light on that today. So this folktale has been around for centuries, but how did it get so firmly cemented into our cultural consciousness? Well, back in 1948, an entomologist in New York State, Dr Howard Curran, decided to do a little experiment, and Dr Curran was actually the curator of insects at the American Museum of Natural History in New York. From 1948 through 56, Dr Curran, along with a group of friends and colleagues who called themselves the original society of the Friends of the Willy Bear, conducted some Rather imaginative research on the subject.

Pam: 2:33

Year after year, dr Curran and his team went to Bear Mountain State Park near Peekskill, new York, to go bear hunting. Well, woolly bear hunting, that is. They would catch as many specimens as they could find, counting the number of reddish-brown segments on their bodies before releasing them. Woolly bear caterpillars are the larvae of the Isabella tiger moth and have thirteen distinct segments, which, according to legend, represent the thirteen weeks of winter. Dr Curran publicly reported his findings and yearly forecasts through the New York Herald Tribune, and they proved accurate every time. After nine years of monitoring, he concluded that there was a correlation, however negligible, between the number of colored segments and the severity of the winter that followed.

Lisa: 3:31

So, to help us shed more light on this story, we are joined by Dr Jon Nese of the Penn State Department of Meteorology and Atmospheric Science. Welcome, Dr Nese. Thank you so much for being here.

Jon Nese: 3:43

My pleasure. Happy to be here.

Lisa: 3:46

Now we mentioned that the amount of dark coloring that we see on the woolly bear in autumn predicts the severity of the winter ahead. And not only that, but the position of this banding determines which portion of the winter will be the harshest. Now that is getting pretty specific. A woolly bear has thirteen segments corresponding to the thirteen weeks of winter. Now for our listeners, Dr Nese, can you remind us what is meteorological winter? Which weeks would those be?

Jon Nese: 4:17

Yeah, for the purposes of statistics it is easier to treat winter as December, january and February. So December one to February twenty-eight or twenty-nine, okay.

Pam: 4:32

So we haven't even started. So as a scientist, Dr Nese, I imagine you would find the study that Dr Curran dida little bit limited. Ten years is a rather small sample size. What kind of data would you need to see in order to consider something like this a useful predictor?

Jon Nese: 4:54

Oh Well, samples of thirty or more are fairly standard in meteorology, so I guess the answer would be thirty. But I don't think we'd find much even if there were thirty.

Lisa: 5:08

Now, in fairness, Dr Curran himself, who was an eminent scientist, knew as much, and in fact most entomologists would tell us that the pigmentation of the woolly bear setae are the bristly hairs, which really aren't fuzzy, they're spiky. It reveals more about the age of the caterpillar than it does about future winter weather, because each time a caterpillar molts or sheds its exoskeleton to grow a larger one, at least one black segment is replaced by a reddish brown one. So the greater number of reddish brown segments just indicates that the caterpillar is older, a later in-star larvae. And also we think that more black setae are produced during periods of wet weather too.

Pam: 5:57

So perhaps woolly bears could be considered useful retrocasters.

Jon Nese: 6:03

You make a good point. They say more about what has happened, and so if we can find correlations between, say, summer rainfall and winter snowfall, then the wooly bears are accurate predictors. But if it was that easy, we'd all be making a lot of money over winter forecasting, and I don't know anybody that does it that well. It still remains one of those places where the secrets need to be unlocked.

Lisa: 6:38

So we've been focusing mainly on winter predictions, but thinking more about weather in general.

Pam: 6:46

Right. Are there any cues or phenomena that you can think of that are reliable predictors?

Jon Nese: 6:53

Well, yeah, I mean, people have always wanted to know the future. I mean, it's as old as time, immortal. You wanna know what's gonna happen tomorrow, not just about the weather. So folks have been taking observations for centuries and there are a few nuggets in there that I use in class. You know, you observe sequences in nature and you observe them enough times and you notice a pattern.

Jon Nese: 7:21

One that sticks out in my mind is a weather folklore that goes like this: Rain around the sun or moon means rain or snow is coming soon. Now, if you look up occasionally you will see kind of it looks like a rainbow around the sun or sometimes at night, the moon, the full moon. It's not a rainbow, it's called a halo, and that phenomenon forms with a specific type of cloud in the sky, a cloud we call cirrostratus, which basically is an ice cloud, and the ice crystals act like prisms, they break the light up into colors and you see a ring around the sun or the moon. Those types of clouds, particularly in the cold season, say from October to April, which is the cold season around here in central Pennsylvania, those clouds often appear in the sky 12 to 24 hours before a storm, and so those who like to observe the sky, notice that I don't know about more often than not, but enough to catch your interest. If you saw a ring around the sun or the moon, 12 to 24 hours later it rained or snowed.

Lisa: 8:40

So the natural world may not be able to provide us with a long range forecast, but certainly it's not a bad idea to pay close attention to your surroundings and to nature, and it often gives us a lot of valuable cues. I agree we kind of alluded to earlier. There are a number of Woolly Bear festivals that are held around the country each year, including in Lewisburg, Pennsylvania. They have a mascot yes, they do. And of course, here in Pennsylvania we love our Groundhog Day. And as someone with a lot of experience in broadcast meteorology too, do you see any value in the various festivals that spring up around these legends?

Jon Nese: 9:26

Hey, I'm pro-festival, okay, I'm pro-festival, so I have no problem whatsoever with finding a reason to have a good time, as long as it's when people begin to take these things seriously, or, shall we say, more seriously than what the science can add or dictate. That's when the scientist part of me kicks in, right?

Lisa: 9:53

right. Well, thank you so much for talking with us today. Dr Nese. Woolly bears may not be good predictors of the coming winter, but they are fascinating nonetheless.

Pam: 10:04

Did you know, for example, that they eat things like dandelions, clover and plantain plants that are often considered weeds in our lawns? Another good reason to encourage diversity in our lawns and landscapes.

Lisa: 10:20

And you know, when we see them crossing our path, they're not lost. They are just headed out to find a good place to hunker down for the winter. They will spend the cold months cozyed up under a blanket of fallen leaves, manufacturing, believe it or not, their very own antifreeze to keep them alive.

Pam: 10:40

So why did the Woolly bear cross the road to find?

Lisa: 10:45

its winter blanket. So Woolly bears may not be great predictors of the winter ahead, but they're prepared for it. Like many other insects, they spend the winter here as larvae under a blanket of fallen leaves. Now you may have heard or read about the Leave the Leaves movement. You know that we shouldn't be so quick to blow all our fallen leaves to the curb in autumn, and there are lots of reasons why that's a good idea. But as far as pollinators are concerned, it's crucial to their survival. So let's talk about what else is going on under there.

Pam: 11:26

Many pollinators spend the winter under leaf litter in the caterpillar stage. An example of that is the Great Spangled Fritillary Butterfly. I see these fritillaries in my yard every year In late summer, early autumn, the females laying eggs on or near patches of violets. The female can lay up to 2,000 eggs, which gives a pretty good odds of depositing eggs near a violent plant. That's a pretty fertile, she sure is.

Pam: 11:58

We live in close proximity to a wooded area so there are various species of violets and in most abundance that common blue violet. Now I can think of, over the years, so many people telling me how do I get rid of all these violets? Yeah, they think they're weeds, that's right. And without violets there would be no fritillaries.

Pam: 12:22

The caterpillar emerges from its eggs about four weeks later it crawls into a protected site in leaf litter and enters diapause until spring. Diapause is a suspended development, sort of like a type of hibernation, and it's made possible because their bodies produce these antifreeze compounds Just like the woolly bears do. Right, yep, that's right. Diapause, putting a pause. The first instar, and that's that caterpillar stage. Between molting, when the fritillary hatches, that caterpillar does not eat until the following spring, as the violet leaves begin to emerge in the spring, the caterpillar begins to eat and eat, getting larger as their host plant begins growing, continuing its metamorphosis.

Pam: 13:14

The caterpillar is velvety black, with several rows of these black spines and a reddish orange at their base. It's very Halloween-y looking. Yes, perfect for this time of year. I have never seen this caterpillar. I wanted to, but I've never seen it because they usually feed at night. That's a pretty super secret kind of a survival strategy when you say I think so Very sneaky. So it's also hard to spot them because they pupate low to the ground on like a log or a rock or a low branch in this loose tent of silk.

Lisa: 13:53

So, unless we spend our time lying on the ground with a flashlight, we're probably not going to see them.

Pam: 13:58

That's right. I'm in bed, by that time.

Lisa: 14:01

Yeah, those days have passed for me.

Lisa: 14:04

Yeah, definitely so. Leaf litter is pretty essential to these gorgeous butterflies, and if we don't provide it, they won't be able to complete their life cycle in our landscape. Now, you know, another pollinator that relies on leaf litter is the red-banded hair-streak butterfly, but instead of using it for shelter, it relies on leaf litter for food. Now, most caterpillars eat the fresh living leaves of trees In fact, two-thirds of all host plants for Lepidoptera are native trees and shrubs but instead the red-banded hair-streak caterpillar feeds on leaf litter-- mainly oak leaf litter-- and 70 other species of mobs do so as well in North America. Now, this is a fairly unusual strategy, because, as far as caterpillars are concerned, dead leaves are fairly nutrient poor. But it must offer some advantages to them, because that is what they do, and some pollinators pupate in leaf litter.

Pam: 15:13

One of our favorite stories is that of the Edwards Hairstreak butterfly. It winters as an egg on the twig of an oak tree. The egg hatches in spring and that tiny caterpillar feeds on catkins and young leaves.

Lisa: 15:27

And as it grows, it develops these glands that secrete a kind of sugary substance which is highly attractive to ants.

Pam: 15:37

So basically, ants protect the caterpillar from predators and parasites.

Lisa: 15:42

So that is a mutualistic relationship that is pretty interesting and beneficial. But that is not the whole story. When the caterpillar is about half grown, around the third instar or so, it starts doing something unusual. So it climbs down off its host tree at dawn and heads for a little den of leaves that its pals, the ants, have constructed for it, and there it will hang out and rest all day long, guarded and tended by its faithful ant friends and kind of I don't know. I think of it as like a little spa, you know, maybe getting an exfoliating treatment or a massage or something, and then at dusk it heads right back up the tree to feed on the leaves all night long.

Pam: 16:36

I can't get that vision out of my head now. A manicure under the leaves. So then at full size. It takes a final trip down to the den to form their chrysalis and then, in about 10 days, it closes, crawling out of their den as an adult butterfly.

Lisa: 16:57

That's a pretty unforgettable story. Or what about my very favorite moth, the Luna moth?

Pam: 17:05

Many people have seen this gorgeous moth as an adult, but the caterpillar eats the leaves from a variety of broadleaf trees. The caterpillar spins a cocoon in the leaves it was eating and then drops to the ground. Where does it drop? To the ground? Under the tree. So if we rake out all those leaves under the tree, we might be throwing out a Luna moth cocoon.

Lisa: 17:33

And that would be very bad, very bad, yeah. So, as all of these stories serve to illustrate, there are many, many good reasons to leave the leaves, as they say, at least as far as pollinators are concerned, definitely. And that brings us to what we're doing in the garden. This month Now, I've been grieving the loss of my summer vegetable garden and cleaning that up. But as for the rest of the landscape, Pam, what are we doing out there?

Pam: 18:05

Well, I'm picking up walnuts, Hundreds and hundreds of walnuts. So, rather than starting up that tedious task of raking and bagging leaves, we can rake them into our gardens and under our trees, where they can return nutrients to the soil. Leaves create a natural mulch that helps suppress weed seeds and they help keep moisture in the soil.

Lisa: 18:32

And leaf litter is an amazing protection for the entire soil community.

Pam: 18:38

So we've been talking about insects using the protection of leaves, but fallen leaves provide food and shelter and nesting material for other wildlife, including lizards, birds, frogs and other insects. These living creatures help keep pests down and increase pollination in the garden.

Lisa: 18:57

And fall is also the perfect time to start a new garden bed. The easy way if you're feeling inspired After choosing your site, you'll want to cut any grass as low as you can and then cover the area with a thick layer of cardboard. And then the next step is to rake some of those fallen leaves on top of the cardboard, or you can even chop them up to cover it up on top A nice thick layer. This process is called sheet mulching and it's much easier on the back, no digging involved. So you just leave it there over the winter and come spring, the cardboard and the leaves will have broken down and you will have a new garden bed just ready for planting hopefully natives.

Pam: 19:44

And it's good to remove leaves from paths for safety reasons, especially at my place, where fallen walnuts will be covered by leaves on walking pads. Does it seem like I'm obsessed with walnuts? But the squirrels are very happy. They love the walnuts, so they shouldn't complain. So any additional leaves can be mixed with grass clippings to create this nutrient-rich compost to add to the garden next spring. That's right.

Lisa: 20:13

And if you would like to learn more about the benefits and uses of fallen leaves in your landscape, or just the benefits of native trees in general, we highly highly recommend that you read Bringing Nature Home and or the Nature of Oaks, both by Douglas Tallamy. These are books that will really open your eyes, give you a whole new perspective on things. They will rock your world.

Pam: 20:42

And remember, as Douglas Tallamy says, the best place for leaves is under the tree that grew them.

Lisa: 20:50

And remember to check out our website snetsingerbutterflygarden. org for plant pollinator and bird directories, sample pollinator garden plans and lots more. Follow us on Facebook for weekly educational posts and if there's something you'd like to learn more about on a future podcast, drop us a line. And please join us next time for more stories on Pollinator Confidential.