Mysteries of the Moth: More Than Meets the Eye

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Guest Information

Dr. David Wagner is an entomologist and professor of ecology and evolutionary biology at the University of Connecticut. His research focuses on the biosystematics of moths and invertebrate conservation. That means he doesn’t only work to understand how moths relate to each other, but also how they interact with the outside world, the threats they face, and how we can work to protect them. He is the author of several books, including Caterpillars of Eastern North America, which won a National Outdoor Book Award in 2006 and is now an app for phones, so you can take Dave’s wisdom with you wherever you go.

Show Notes & Links

In this episode, we talk about the diversity of moths around the world and within the US. Moths outnumber butterflies in abundance and diversity and play incredibly important roles including pollination. Many moths are still being discovered and scientists are still learning about their life histories. Moths are threatened by loss of habitat and climate change, especially drought and an increase of nitrogen in the environment. 

Transcript

Rachel: Welcome to Bug Banter with the Xerces Society where we explore the world of invertebrates and discover how to help these extraordinary animals. If you want to support our work go to xerces.org/give.

Matthew: Hello! I'm Matthew Shepherd in Portland, Oregon.

Rachel: And I'm Rachel Dunham in Missoula, Montana.

Matthew: Moths are largely creatures of the night, which means they may not get as much publicity as their day-flying relative, butterflies. Moths are more diverse than butterflies, probably more abundant, and most certainly play a key role in the natural world. Honestly, moths are some of the coolest insects and we are excited to highlight them in today’s episode.

Matthew: Joining us to talk about moths is Dr. David Wagner, an entomologist and professor of ecology and evolutionary biology at the University of Connecticut. His research focuses on the biosystematics of moths and invertebrate conservation. That means he doesn’t only work to understand how moths relate to each other, but also how they interact with the outside world and how we can work to protect them. He is the author of several books, including Caterpillars of Eastern North America, which won a National Outdoor Book Award in 2006 and is now an app for phones, so you can take Dave’s wisdom with you wherever you go.

Matthew: Welcome, Dave!

Dave: Yeah, it's great to be here.

Rachel: Yeah, thanks for joining us. We're excited. So, to start us off, can you tell us what makes a moth a moth? How are they different from butterflies?

Dave: That's the toughest question you could ask. It's hard to start off with that one, Rachel, but—. Butterflies are moths, and that's why it's so hard for us to tell them apart. And so, on the tree of life, there's this really giant limb that's the Lepidoptera, the butterflies and moths, which might have 300,000 leaves on it. We're not exactly certain. But, it's a hyper-diverse, very successful, extremely important ecologically—but we don't know exactly how many species, but we know it's big. And this one area or twig on it has the butterflies, and they're day-flying moths. And so—and in fact, we now believe that there's a group of moths between our two most familiar groups of butterflies. 

Dave: So, if we take sort of the swallowtails and the true butterflies and the skippers, there's a group that sits right between them called the butterfly moths that are in the Neotropics. And so that's sort of new information that's spun out of all the molecular biology and sequencing we're doing these days. So, the butterflies now been redefined to include these nocturnal moths—or what have you, whatever—butterfly moths. And we're also finding out that the differences between butterflies and moths are really almost just a vernacular understanding, or a common name that we've all come to understand. 

Dave: But there's many groups of moths that are diurnal, that fly around in the daytime like butterflies. And one of the characteristics we always seem to focus on is the antennae. So, our two groups of butterflies, the skippers and true butterflies, have a knobbed antenna. But with 300,000 species or more moths, be assured there are moths—day-flying moths even—also with knobbed antennae. But if you're in the United States or in most temperate regions, you won't see these exceptional things. And so, anything you see flying around with, you know—in the daytime, with knobbed antennae—good chance it's a butterfly.

Rachel: Thank you. That is a hard question to answer, haha!

Matthew: Yeah, we like to start with, you know, an easy one to get you settled in. Yeah, I guess in a way, you might have just answered this one, because I was gonna ask how many species of moth there are in the world. And you said about 300,000 Lepidoptera.

Dave: Well, it's a guess. You know, I don't know. We have about over 160,000 named right now. But for some groups in the tropics, we know there's large numbers that are unnamed. And now with molecular biology, when we can look at the genes for some of these things, we're finding out that some of our species are actually two species. And so, there's a lot of cryptic diversity out there as well. And there's—we know very, very little about some of the microlepidoptera, these guys that are flying around at night, and they're very small and poorly known, and really represent a galaxy for discovery for future generations. If anybody's looking for a hobby or a career—microlepidoptera, there will always be a place for you. 

Matthew: And I mean, what about in North America? Do we have a sense of how many species? I assume we're still discovering them?

Dave: Oh, for sure! So the new checklist just came out at the end of last year, and I think they just—they recognize over 13,000 butterflies. And well, I think that may be just the moths. So, 13,000 moths, primarily. And we discover new species fairly frequently. I just named a new species of giant silk moth from deep limestone creeks in Austin, Texas. And so, there's a lot of really exciting discoveries. 

Dave: I think we'll probably be adding two or three giant silk moths to our list of U.S. moths. And so, if that's the case in the United States, know that in the Neotropics there are many, many groups where less than half of the species are known. So again, lots of opportunity for more study. And the more, the merrier, in terms of—we still—you know, we're in a biodiversity crisis. 

Dave: We're in the Anthropocene. And I'm afraid that many of these things are gonna disappear before we've even had a chance to give them a name. So you know moths certainly provide a lot of opportunity for even backyard naturalists and people that want to travel—especially to the Neotropics, which are certainly the cradle of diversity for Lepidoptera—just taking pictures with their camera or, you know, their phone. Getting these posted on iNaturalist is a contribution, a really important one actually. 

Dave: And so, the more we can do with the moths, the better. And moths are challenging, just because, you know, the time we go in at night to eat dinner—or have a drink, or whatever we do, get some sleep—that's the time when all this diversity is peaking. And so, it's very understudied. So much of what we know in biology is what we can see in the daytime, and finding out what's going on at night is equally exciting. 

Dave: And maybe in some cases, we really need to understand. Like, I study caterpillars, and there may be more caterpillar action at night than there is in the daytime. So, all these ecologists and conservation biologists and all of us are missing half the story, or more than half the story.

Matthew: Yeah, and we're definitely visual animals, as humans.

Dave: Yeah. 

Matthew: And so, you know, we take note more about what we see maybe than—and that must add a layer of challenge when you're going out in the dark to look for potentially small things. And I was intrigued when you said you just named a new species of giant silk moth, because that must be a fairly big one.  And it's just the idea that, you know, like even the big moths have not all been identified and understood yet.

Dave: Right. But I have to say that it's not the—it's one of the smallest giant moths in the world. Haha. 

Mathew: Okay haha. 

Dave: And so, the name of the paper is like “A New Giant Silk Moth from Texas: Not Everything in Texas is Big.”

Everyone: Haha! 

Matthew: Yeah, ‘cause I know—I mean globally, some moths can be huge, can’t they?

Dave: Oh, yeah. Yeah. So, the biggest, and maybe among the most mysterious, is the white witch. And its males—and it's usually the female that's larger—but for the white witch, it's the male, and we don't know why. But it can have a wingspan of up to 12 inches. We still don't know its caterpillar very well or its life history, which is amazing. So, the largest—maybe the largest—moth in the world, we still don't know much about. So again, lots of opportunity here.

Dave: The giant Atlas moth has the wingspan about 11 inches as well, and it's one of the largest insects in the world.

Matthew: Yeah, no, that's spectacular, for sure. And you mentioned that—how hard it was to see the micromoths. I mean at night, obviously. I think even in the day they can be hard. I mean, they get really tiny, don't they?

Dave: Aerial plankton, sometimes. 

Matthew: Haha!

Dave: Yeah, so. But they're so beautiful under a scope. One take home lesson from this whole conversation that we're having, is that if you can magnify these insects, they become so much more interesting and engaging and capture your soul or psyche. But especially these leaf miners and tiny moths can be resplendent—really gorgeous creatures under a scope.

Dave: Or if—I always carry a hand lens around, and I find nature so much more interesting when I'm wearing a hand lens, and I can look at their eyes and look at—you know, things that you think might be brown from a distance of three feet, you get out your hand lens and it's actually purple and yellow. There's no brown on the animal whatsoever. And it's that magnification. It's your brain telling you it's brown, just because it's far away and you can't discern the colors. But using our digital cameras, and now our phones and a hand lens, or if you have access, especially a microscope. 

Dave: If you can give a kid a microscope, it'll change their life. And there's just no question that seeing all the ultrastructure and the biomechanics and things that can't be seen with a naked eye will change how you feel about these animals.

Matthew: Several years ago, I used to help run a bug fest at a local nature park and the two most popular activities every year were—one, going out with a net to catch stuff and then bringing it back to have someone say, "Oh, this is what you found." And the other one was—we just had a rank of microscopes setup, and for many of the kids—even their parents—this is the first time they've really spent time looking through a microscope for them to see the things up close and really see the details and the structures and the beauty. 

Matthew: I know one thing that has brought moths to our attention is the fact that some species are pests. And I say "pest" because I know it's a term that has different interpretations. But we when we think about some of the impacts, some of the interactions we have with moths, I think of clothes moths. You know, there are some that are pests of—you know, eat stored food. There are some of the well-known ones—cotton bollworm and corn earworm, and for sure, I mean, like gypsy moths and some of the forest species. 

Dave: Absolutely.

Matthew: And you know, with 100,000 species, this is a really small number of the species, and yet have really heavily influenced public perception.

Dave: Oh, for sure. Yeah, if anybody's eating a codling moth larvae in their apple, or something like that, I mean—. 

Everyone: Haha. 

Dave: In fact, you know, it's funny because people really want fruits, and all of their vegetables to be perfect. And so that means, oftentimes, using pesticides to make sure that our fruits and vegetables are cosmetically free of any pests. 

Dave: But, you know, that's quite a sacrifice, because in many ways, it would be much better and safer and healthier actually if we accepted some small level of blemishes or insects. Yeah, especially smaller things that you could barely see, rather than have some pesticides, you know, sprayed on this food that we're giving our children, and what have you, so. 

Dave: Yeah, the pest thing is really important. Because insects are responsible, particularly caterpillars, are responsible for tremendous amount of damage worldwide. And they're part of how we want to do agriculture differently so we increase our yields and use less pesticides.

Dave: But like, I would guess that it's less than .1% that are really sort of economically important. And so, 99% or more are really important in terms of ecosystem function and ecosystem services, and provide many important services for nature. And the most obvious one that I can think of is they're really sort of the hamburger, or the tethering, or the fabric of the tree of life. In terms of—almost anything on land has got insects involved in it. And especially Lepidoptera, in terms of being really important—maintaining their diets and their relationships among these creatures on the tree of life. 

Dave: You know, if you go out into the forest or a grassland and you start looking for insect biomass, you want to know what's feeding what and making all of these creatures work, or passing nutrients, passing energy from one trophic level to the next. Well, caterpillars, by day or when they're young, are really important in terms of making insectivores or feeding insectivores—making baby birds. You know, spring would be entirely silent without caterpillars. But then at night, the moths also are the most important biomass in terrestrial ecosystems and insect biomass. 

Dave: And it's unbelievable the amounts that are out there. There's this bridge in Austin, Texas. I think it's called the Congress Avenue Bridge, with, you know, a million bats—maybe several million. And they eat like 20,000 pounds of moths a night, particularly when they're nursing their pups, you know. And some estimates are 30,000 pounds of moths a night just for this one colony. 

Dave: So, caterpillars and the adults are really fundamentally important. And it's kind of like one of those things you can't live with them and you can't live without them right? 

Rachel: Haha. 

Dave: And you know there's so much focus these days on pollination, right? And we really recognize that as an exceedingly important part of the services—the ecosystem services, the ecosystem function that insects do. And bees get all the credit—and butterflies a little, and maybe even too much. But for every butterfly that you see flying around in the daytime, there's at least 15, maybe 17 species of moths at night that are doing quite a bit of business. 

Dave: So, we don't really know much about the importance of moths in terms of pollination. But, just about every white flower you see might be white because it's interested in a moth pollinator. And the story that I like to tell the most is that plants that are fragrant—so, these things we like for boutonnières, or we like to give our partners or our loved ones in terms of flowers, or, you know, a nice bouquet—things that are fragrant. Almost all of those fragrances that you would find in jasmine, narcissus, gardenia, honeysuckle, all of these—some of our favorite aromas or scents on the planet—those are signals that plants are putting out for moths. Moths have to get their business done at night. They can't see, as you said, or visual cues aren't terribly important. 

Dave: And so, these plants are making these compounds to attract the moths so they can get their pollen from one flower to the next. So they very much enrich our life indirectly because of their pollination services at night. Jasmine, in particular, it's like the queen of the cosmetics industry. It's what we put in—just about every perfume has some fraction of jasmine, and you can thank my moths for that. You know, that just wouldn't be a substance if there weren't this insect-plant interaction and a lot going on at night that we still don't know much about. So, I don't think moths get nearly enough credit, and they certainly are—you know, maybe with our new technology and our new cameras we'll be able to study some of these phenomena that happen at night more easily than we've had up to this point.

Rachel: Yeah, I don't think people realize how many just species of moths there are, in comparison to butterflies. And you had said 13,000 in North America. Is that right?

Dave: Yeah, right, yeah.

Rachel: So, you'd previously talked a bit about sort of hotspots of diversity. Where would those be? Particularly in, you know, the world and in North America? And then what is it about these places that support so many different species of moths?

Dave: Well the hotspot for North America, north of Mexico, would be the Chiricahua Mountains in southeastern Arizona. So, you get 10,000 feet of elevation right on the Mexican border, and—but in general, for just about any group of organisms—essentially all insects, at some level—you're gonna be seeing highest diversity in sort of the lower, mid-elevations of a mountain range. Because you get the north slope. You get the south slope. Nearly all mountains have lots of different kinds of hydrology or water bodies. You get the east slope and the west slope. And so, that's where diversity peaks. So, as you come out of a, you know, some sort of plane and move up into those lower canyons. I think the Patagonia count in the mountains—the Sky Islands in southeastern Arizona, near the Chiricahua—has the highest butterfly count in North America. So they sometimes get up close to 100 species in a single butterfly count, which is just phenomenal.

Rachel: Wow!

Dave: In North America, which includes that—really North America is everything down to Panama. But Mexico is incredibly diverse—and really a lot of unsampled areas. Unfortunately, it's really tough to work in these days, but it's enormously important in terms of any kind of iNaturalist observations that people can make, and connections. That's certainly where I hope to do some work over the course of the next decade. Two of my students work there. Actually, one of my students is going next week.

Dave: But in in terms of the world, obviously, the tropics are going to be the richest. I don't really know, but I'm guessing 80% of all Lepidoptera will be from the tropics. And not just the tropics, but especially the Neotropics. So, South America, along the equator and the mountains. Any mountains near there will be the peak of Lepidoptera and diversity.

Dave: There's supposed to be one road—if you're in Peru and you go over the top of the Andes and start dropping down into the Amazon Basin—I think they recorded over—I don't know the exact number, but it might be as many as 2,500 species of butterflies just on this one road.

Matthew: Wow!

Dave: It's phenomenal. And every time they go they find new species—new for the road, when they take this transect—and new species of butterflies that are undescribed. But, it's just phenomenal, when you start to drop down into the Amazon basin, how diverse the butterfly and moths are. But that's probably true of the katydids and the bees and there's certain groups. I shouldn't say bees necessarily. They like dry conditions, and so actually, the American West is, I think, the peak in the world for diversity of the wild bees.

Dave: If I had to pick one country in the world with the highest butterfly and moth diversity, I’d pick Colombia. It's actually pretty far, you know, moving away from the equator. But it's got three distinct mountain ranges. And so, having three distinct mountain ranges with tremendous elevational range, and all the different water and jungles involved, I think—you know, it's like birds, probably pretty reflective of birds. And we can often use birds as a proxy for insect diversity. It's certainly more well-known and studied. And so, where you have really high bird diversity, you'll probably have pretty high butterfly diversity.

Matthew: The next question I wanted to ask you is, like, are there any moths you find particularly interesting or you are particularly fond of? It's like, I know, that you have—you know, your studies are focused on ghosts moths and leaf miners. And so, part of me—it's like, I'm curious to know what drew you to those moths. I mean they seem so different from each other.

Dave: Well, you know, I joke that my favorite moth is the next one. 

Everyone: Haha!

Dave: But I really love moth groups where the adults are really difficult to tell apart—often, they're incorrect in our checklists, they're incorrect in our museums, they're incorrect on our websites—but where their caterpillars tell a completely different story. And the caterpillars get it exactly right. Like, if you're looking at say DNA, and you have the caterpillars, all of the sudden, the lights go on and you can get the taxonomy exactly right, and realize how many species there are, and sort the adults and collections differently, and finally get them correct.

Dave: And so I call—that's when the caterpillars are the Rosetta Stone. And there's a lot of groups of the caterpillars tell us a lot more. So, some of these moths are really short lived. Some of them don't even feed. I kid around—they’re gonads with wings. Haha. And so they have got one purpose, and it's to reproduce. And then get rid of those eggs and disperse. Right? So, it's really about—it's all or nothing. It's reproduction. All hands on deck. 

Dave: There's also some moths that live six to eight months and perhaps even longer, perhaps up to a year in the tropics, or something. Not many. The white witch that we talked about has a very long lifespan, when it's in diapause, or when it's in a pre-reproductive state. But, caterpillars, by contrast, are on those plants for days and days and days and days, and you have all of these visual predators. They, you know—especially birds. It's amazing to watch a bird fly into a tree or a shrub in your yard, and see how long it takes them to find one caterpillar to take back to the nest. Oftentimes they're in that shrub for two to three seconds, and they'll pull out one or two caterpillars, and you can walk up to the same shrub and spend 30 minutes trying to find—. It's just, it's just amazing.

Dave: So, these caterpillars are under tremendous pressure from these visual predators. Lizards are probably just as good. Some caterpillar-eating snakes are really good. And we shouldn't forget our ancestors, the monkeys. You know, they're very diverse in the tropics, and very abundant. They're up in the canopy, and they are visual predators and frankly, caterpillars are pretty good to eat. They're very high in protein. Not all of them are chemically protected. So again, that's how you make baby birds. It's with caterpillars. You know, spiders play a secondary role. 

Dave: But the point of this is that caterpillars have to be really camouflaged, or have some strategy for staying alive because they're under such strong selection pressure. They don't have the luxury of flying around only at night, when visual predators are, you know, out of a job or have to wait ‘til the sun comes up. And so, they tend to have more intricate phenotypes. They tend to have ways that make them become invisible on the plants they're feeding on. They have to figure out a way that birds aren't gonna be searching for them. But that—you know, if you're a biosystematist or taxonomist, those are the characters that I can use to get the taxonomy right for the first time, or discover new species. 

Dave: I can't tell you—I would say that when I'm in the field, I probably discover a new species in Western North America at least once a week. I discover—I find the caterpillar for the first time, and I look at it and say, "Wait a second, that's not the same caterpillar as the one in Arizona, and they're called the same thing." And so I get to discover new species of science on a weekly basis based on the caterpillar.

Dave: So, I love caterpillars, right? And that—for that reason, too, that's why you can make a field guide to caterpillars that people find useful, because the caterpillars are so distinct from one another that a field guide really works.

Matthew: Yeah, that's excellent. And I know you were talking about caterpillars on plants, but I know caterpillars eat all sorts of other things. I mean I've read about one that eats the shells of dead tortoises, for example. 

Dave: Right. 

Matthew: I mean, I'm guessing that there must be other caterpillars that would have what we might consider to be unusual tastes. But, I mean, not to them obviously, cause it's their favorite food.

Dave: Right, right. Of course. They eat everything, every plant part that you can imagine. So, there's a lot going on underground that we can't appreciate. There's a lot inside stems that we can't appreciate. We already talked about the codling moth. So there's—the seeds and fruits of a plant are about as nutritious as any tissue that you can imagine. And so, there's suites and suites of Lepidoptera caterpillars that focus just on fruits and seeds and that sort of thing. 

Dave: And we just—the Holy Grail for moth life histories in the East Coast was the pink star moth, this beautiful pink and yellow moth. And we—but no one could ever find the larva, and this high school student last month was walking with Sam Jaffe from the caterpillar lab. And Sam had probably been to this same field 200 or 300 times, But the high school student, Logan, he was naïve predator, and he didn't know where to look and he didn't know what he should have been looking on to find caterpillars. So, he stared down at this sort of brownish plant that had already kind of gone by, and was easily missed, and he saw this caterpillar. Because he's looking on the "wrong" plant. We're really sure that it's gonna turn out to be the pink star moth. But there's all these caterpillars that feed on senescent plants. So, we think they're done. They don't have any flowers anymore. They're not pretty. And yet there's a whole caterpillar fauna that really like those senescent plants, that are really protecting their seeds and their fruits and that sort of thing.

Dave: So, that that's been really fun. There's caterpillars in Hawaii that eat fruit flies. So, they lean back and they have really long legs and they grab any insect that is on them and then pull them into their mouth and eat them. And so that's certainly crazy.

Dave: You talked about eating wool. So, the ones that eat turtle shell are able to break down the sulfur bond that's in keratin. So, keratin—our nails are keratin, the horns of many animals are keratin. This is a protein that's a cross link—that disulfide bonds—that make them undigestible to most of the life on this planet. But this one group of moths, the teneids, are able to digest those bonds so they can eat horns, they can eat shells, and they can eat our woolens, which is pretty unusual. 

Dave: So—oh, here's a good one! This probably may be my best. It's that wax moths, a pest. Yeah, by, you know—if you're a beekeeper, wax moths are really bad. But, you know, one man's pest is another person's hero, or whatever. So, this wax moth has a microbiome. So, inside their gut, their intestine, they're able to eat plastic and metabolize that and turn it into decomposed plastic.

Dave: So, it has a potential role in, you know, taking care of plastic going forward in the future. So that's highly unusual. But there's the wax moth and some of its relatives that have these same enzymes and similar gut fauna that allows them to digest what is presumably undigestible to most creatures on the planet.

Matthew: Wow! I love the story of the high school student going out and after all the time of people trying to figure this out, and it was someone—. I mean, I always love those anecdotes because it just shows us how much we, as individuals, can potentially discover and what we might be able to contribute to broader knowledge, which I think are just so inspiring.

Dave: Right. So, I just wrote a book on moths, Moths of the World. And the epilogue of this field guide is that we live on a very beautiful planet. And that it's quite unknown at this point, relative to—you know, if a high school student can still make really important discoveries, there's a lot to be done. But now that we've entered the Anthropocene, and with climate change accelerating the loss of biodiversity, it's really urgent that we start paying attention to these little things that run the world and try to find out as much as we can about these creatures.

Matthew: Yeah, I know that I was going to ask you about conservation and drivers of decline, ‘cause I know that a good chunk of your research is being focused on that. So, you mentioned climate change. That's, obviously I'm assuming, one reason for declining populations. What are the other ones?

Dave: Well, I divide it into two tiers. So, I've written about this actually in an annual review article that's been cited more than a thousand times, and also a perspective in the Proceedings of the National Academy [of Sciences] about what those drivers might be. 

Dave: And so the upper tier—the three, by far, in my mind, yeah, is—the one that everybody knows about is habitat loss and degradation. And historically, those two things, habitat loss and degradation has been the primary driver of biodiversity loss around the planet. And then a second one, that I think is really important now and may be overtaking that, is climate change. And we can dissect what climate change is and why. But the third thing is agricultural intensification. So, this new mega-agriculture, this industrialized agriculture on scales that are unprecedented with lots and lots of chemicals, is now right up there in the top three. 

Dave: And then I think it's a pretty big step down to the others—you know some people don't agree with me—but where you have pesticides, pollution, invasive species. And there's really just a very long list.

Dave: Light pollution, I think, is way more important than we realize right now. There's a lot of new research coming out that light pollution is really difficult on nearly all insects, but you know, especially moths. Every light that's left on at night is a feeding station for bats, you know, within two days. Anything that's around that light in the morning is gobbled up by birds. And then there's a whole suite of things that run around on the ground under lights that we don't have any, you know, feel for—mice and, you know, predaceous beetles, and other insectivores. And so lights by themselves that are left on all night are pretty challenging. And I think we're going to find that that's a, you know, far more important driver. 

Dave: Urbanization, obviously, is going to be another driver. You know, one that we don't talk about, and probably might be unfamiliar to many people listening to this is nitrification. So, we've doubled the amount of nitrogen that the planet had when we—. So, for the last, let's say, 20,000 years or 13,000 years we've been in the Holocene. And there's been a biogenic chemical constitution to our planet, and so much nitrogen, so much phosphorus, and these other elements were available for life. 

Dave: And we've taken that formula, especially nitrogen, which is limiting—that's what we put on our lawns, that's what we put in our gardens to make our plants grow faster—we've doubled that by trapping nitrogen in the atmosphere and adding it. So, that's going to change all plant distributions on the planet. But the, you know, other thing is that fossil fuels—when we burn fossil fuels, we produce a lot of nitrates, and nitrates and what they're doing is coming down through atmospheric deposition all around the planet. And so, we have all of these ecosystems that have evolved without nitrogen. 

Dave: So, there's many soils in the tropics that are almost devoid of nutrients. And now we're gonna be putting nitrogen into those, and our bogs and our pine barons and other really nutrient-starved ecosystems. And the plants and the animals and everything have been evolving for millennia, you know, to get by and compete and be competitive in these ecosystems. And now that we put nitrogen into them, common lawn weeds and inventives can come into these communities and really change the rules of life. And so, nitrogen pollution is far more important than it's getting credit for right now.

Dave: And just to return to one other thing is—climate change is huge. When you hear people talk about climate change, the focus is always on 1 degree C, or whether or not the planet's gonna heat up by 1.5 degrees centigrade, or whether it's gonna go to 2 or even higher. And so, the focus really gets drawn to temperature, and that ultimately that's the problem, in that the temperature is the amount of energy that ends up being in the oceans and driving our climate cycles. 

Dave: But really, the proximate killer for insects, I think, is water. And I think we need to be spending a lot more time thinking about water, fresh water, how much is used in agriculture. Insects, they can't store water. They're too small, you know, and they have all this surface area. And when they breath, they have direct air delivery to every cell group in the body. That makes you incredibly sensitive to desiccation when you fly, just across the field. You have to tank up. You have to get more nectar. 

Dave: But anyway, I actually think it's the drought. And what we euphemistically call "climate anomalies" is really going to be what's driving that decline of butterflies in the in the American Southwest right now, and really going to be challenging for insect life. And, you know, 1 degree or 2 degrees centigrade, for an insect is kind of nothing. A lot of these insects are cold blooded. They go through—some of them can go through swings at 40 or 50 degrees centigrade in one day. But they can't handle major swings in water. That's why droughts are very difficult. And I think some of the insect decline—a lot of the insect decline the planet is really linked to drought events. And it's something we gotta pay more attention to.

Rachel: Yeah, it feels very overwhelming to hear these list of things that are obviously impacting insects and moths. And I mean, we try to end on like a hopeful like, "There are things that we can do. It's not all doom and gloom." And there are things that we can do to help insects. 

Dave: Absolutely! 

Rachel: So, specifically for moths, you know, whether someone is a gardener or lives in an apartment complex and has no interest in gardening or doesn't have a yard, like what can people do to help to help moths?

Dave: Well for people who do have a yard, you could rewild just part of it. I like—I love the idea. I don't know what the actual numbers are, but I heard Doug Tallamy and others say that if all of us rewild just 10% of our yard, it'd be almost as much land or more land than all the national parks. And so that's just a really fun idea. And if you can't rewild your own yard, you could rewild part of your community. So, there's always a school where you could be involved with building a pollinator garden or a moth garden or a butterfly garden. They're very popular these days, and having kids turn dirt and soil and plant things, I think, is very powerful.

Dave: And or, you know, watching some of these caterpillars metamorphose into adults, I think, is very powerful. So education is huge. So, you know, if we're all lost souls, you know, who are over 20, and we're not gonna change how our minds about how we vote or how we live our lives, or how much meat we eat, or how much red meat, whatever—at least think about education and the next generation. Because on the grand scheme of things, you know, the planet's 4.5 billion years old. And if we just did a really good job with educating the middle schoolers and the next generation, we'd have a whole different kind of cadre of people—foot soldiers for nature that would vote, and act, and change our views about the climate and the global South, and all the things that we really need to do. So, education is absolutely critical. 

Dave: Changing people's perceptions about insects is critical. And so again, that's education and knowledge and science. So, those are huge things. Of course, joining the right nonprofits, if you can afford to do so, and supporting those. They all have political leverage, and that's enormously important. The most important thing, without question—I mean, I can ride my bike, and I can eat low on the food chain, and I can do all these right things. But, yeah, that's only you. And it's really good that it's you, and you're setting an example for others. I think how you conduct yourself matters. 

Dave: But really, everybody needs to take time to help change and influence policy. Think about what you do in the big picture, and take some time to change how people think, either to educate or change laws. That's the most important thing. But beyond that, there's just so many things we can do. Just contributing to iNaturalist and getting out in nature and taking pictures—that data is now becoming the most important data on the planet to make decisions about biodiversity. So, iNaturalist alone supplies more data on where things are found—butterfly counts supply more data on where things are found—than all the museums and all the scientists put together. 

Dave: Scientists are only a tiny fraction of the human population. But when you add all the people that can do stuff in their backyards, take pictures in their backyard, walk the dog and take pictures, and share this information, it's enormously powerful for making really important conservation decisions. So, there's a lot you can do. What you plant manners. I mean, everybody knows this, but plant natives. Right? And don't go too far into the these ornamentals. You might as well have plastic plants in your yard and put up a sign that birds aren't welcome. You need to plant native plants.

Matthew: Yeah. Well, thank you so much for the last—well nearly an hour I think we've been talking now. It has been really interesting. I mean, it's fascinating to hear you talk about moths and, you know, their biology and the relationships and the importance that they have for all of our other wildlife, and I mean, indeed our lives as well. So, thank you for that.

Matthew: We have our last question, which is always our favorite—which is: what inspired you to become an entomologist, and I guess eventually led you to study moths?

Dave: I don't know. I think I got whatever those genes are for hunter-gatherers. I think I got like a double dose of those, or something like that.

Mathew: Haha. 

Dave: Because I always picked up stuff, and I—you know, shells, coins, stamps. So, I was a bit of the gatherer. But it was insects that really attracted my attention. And my uncle—I'll tell you this, Matt, because you brought it up. He claims he gave me a net when I was two or three years old to distract me. I was on a farm in Missouri, in the Ozarks, and there was no turning back after that. 

Dave: My parents gave me a microscope when I was really young. Maybe fourth or fifth grade? And I know that had a huge impact on me. When I—the microscope came with like a box of slides. And there was a disarticulated honey bee. And I couldn't believe how interesting the legs were and where the pollen was gonna be stored in this corbicula on the hind leg. And their eyes were just amazing. And so, that—I sort of became an entomologist. I didn't think there was a career in entomology. And, you know, when I applied to college, I didn't think—you know, "Well, who's a career entomologist?" You know? So, I thought I would be a forest ranger. But you know, once I got to college, I realized—I took a couple classes in entomology and really liked it. 

Dave: So, yeah. You know, it starts young. And, you know, getting our kids out in the wild with this and being enthusiastic and fun and making discoveries, is really, you know, what it's about. Rearing caterpillars, having a little— you know, catching fireflies, it's just magical, you know. So, there's just so many different experiences you can have with your kids that I think are really formative.

Matthew: Yeah, definitely, Yeah, If you can get kids outside—get them literally hands-on with insects, it can be a lasting.

Dave: Yeah, making their own discoveries, Bringing stuff home and putting in a jar for 24 hours, and they then letting it go again. Or, you know, watching metamorphosis is life changing. I think it's so interesting and a metaphor of their own life and their own development, you know. And that it's the ugly duckling story, but it's real, you know. It's the Cinderella story, but, you know, there it is, right in front of your eyes.

Rachel: It's so inspiring to hear your story, but also how important it is to get kids outside. But thank you, Dave, so much, like Matthew said, for sharing your knowledge and taking time to hang out with us today. 

Dave: Sure! No, great. Thank you. It was really fun. So, we'll see you guys down the road.

Matthew: Bug Banter is brought to you by the Xerces Society, a donor-supported nonprofit that is working to protect insects and other invertebrates—the life that sustains us. 

Matthew: If you’re already a donor, thank you so much. If you want to support our work go to xerces.org/donate. For information about this podcast and show notes go to xerces.org/bugbanter.