a firefly primer, with lynn frierson faust (win her field guide)

FIREFLIES: THEY NEVER FAIL to bring out that sense of first-time wonder, the excitement of a child on a summer camping trip when the sky darkens and the flashing begins. But until a new field guide reached my desk, I hardly knew anything about them beyond that feeling. In time for their flight season this year, I wanted to get a Firefly 101, so I know more about who they are and what they’re doing out there.

Who better to get schooled in the world of fireflies by than Lynn Frierson Faust, author of “Fireflies, Glow-worms, and Lightning Bugs” from the University of Georgia Press, a guide to the natural history and identification of fireflies of the Eastern and Central U.S. and Canada.

Read along as you listen to the May 14, 2018 edition of my public-radio show and podcast using the player below. You can subscribe to all future editions on iTunes or Stitcher (and browse my archive of podcasts here).

Plus: Enter to win a copy of the firefly field guide by commenting in the box at the very bottom of this page.

firefly q&a with lynn frierson faust


Q. I have to say that despite the fact that the book is about a complex subject, and something I knew nothing about other than as I just said in the intro my wonder at them, that it’s written in such a way that a layperson can actually read it. You really, among all the technical details, your continuing excitement over the subject really (ha-ha) shines through [laughter], so yes.

A. Well, thank you. That was my goal. I wanted it scientifically accurate, but I wanted to write it in a way that was accessible to everyone, because everyone likes fireflies—or lightning bugs as we call them down here.

Q. Yes, even the little touches, like in the margins on some pages you put quotes about them from history or from literature. There’s this one I loved. It was anonymous from the late 1800s. It says:

The lightning bug is brilliant

but he hasn’t any mind

he blunders through existence

with his headlight on behind.

[Laughter.] He’s got his light on backwards.

A. There’s one quote of course I can’t find it now; I need both hands, but one from the Hudson River Valley, up where you are.

Q. So they’ve been capturing mankind’s attention for thousands of years–I think you say in the book it was even in Chinese writings.

A. Since the beginning of writings, we find references to fireflies.

Q. How long have they been a fascination for you?

A. Well, all my life I’ve loved them. I’m blessed to live in the mountains of East Tennessee, and we have very rich diversity and lots of different species here. So I grew up liking them, and thinking they were magic. But also when you always have it, you don’t appreciate it. Like some people from out West will come visit or whatever, and they go nuts when they see them because they have never witnessed them before.

But then in my late 30s, this is 26 years ago, I switched from just loving them as a thing of beauty to starting to really pay attention to them when I began working with research teams up in the Smokies. Really like everyone else pretty much—everyone thinks there’s only one kind of lightning bug, one kind of firefly. And so my journey began then when I realized there’s more than one type, and it went on from there and kind of expanded to the whole world. [Laughter.] But mainly the Eastern U.S.

Q. How many species are there, in the East or in the book? Give us a sense of the diversity.

A. I cover in detail 60 to 70 species in the book then in exquisite detail, up to 8 to 10 pages per species. The general number—and it’s always changing and everyone can argue about it if you’re a splitter or a lumper—but generally we say 125 species more or less are in North America. So of course we always include Canada because the fireflies don’t know boundaries; they know habitat and so they freely move everywhere.

Q. Right.

A. One-hundred twenty-five would be a number you could sort of hang onto.

Q. O.K. Because I mean—and you just alluded to this—here in the Northeast where I am, growing up and living up, when I’d see the first ones in the beginning of summer, I always thought “fireflies” like “robins,” or do you know what I mean? It was one thing, or “raccoon.” [Laughter.] I didn’t know, I thought it was a homogeneous group of one species out there on a summer night but it’s not even in my literal backyard, there are more than one putting on that show potentially, yes?

A. Yes. You have lots of them up your way, and particularly as you get, they’re very habitat-specific, so similar to wildflowers. I’m assuming you have lots of nature lovers listening, wildflowers, trees, anything like that, many are habitat-specific and many of the firefly species are also. So some will be found only near a marsh area, or in a deep forest, or some are more open species. Some are up in treetops and some are down low, and all of those represent usually different species.

Q. So what is a firefly? What is it? [Above, Photuris potomaca photographed in New Jersey, in July 2014.]

A. It’s a beetle. It’s not a fly, and it’s not a bug like “lightning bug.” It is in the beetle family because it has the hard wing covers.

Q. Elytra?

A. Called elytra.

Q. Yes.

A. Yes. Those protect the real wings underneath. And to be a lightning bug, you have to glow as a larvae, as a baby. Some of them that do not flash or glow as adults, they still glowed as babies, as larvae, and that’s one of the criteria for being a lightning bug.

Another one is—and there are some exceptions—but they usually can retract their head all the way under the shield that’s above their head, called the pronotum, and they can fully retract their head almost like a little turtle. Many similar species, the soldier beetles and the click beetles, and some of those that looked alike, they can’t do that; their heads stick out all the time.

A. Those are two simple things.

Q. I was going to ask about that because they’re not (ha-ha) flashy-looking other than the fact that they flash but they’re kind of blackish, with maybe a little bit of reddish-rusty whatever color by the head and not much going on in terms of flashiness. When you just look at the insect, and in fact some of those other insects that you just mentioned, they seem to mimic the firefly—they look a lot alike. You actually have a great sort of grid page of pictures in the book: lichen moths, soldier beetles, and assassin bugs that look like fireflies. Why would another insect want to have evolved that way; why would it want to look like a firefly?

A. Well, it’s a great question and one that scientist are still looking into deeply. There’s a long word, aposematic.

Q. Yes.

A. It just means protective coloration or actually dangerous. Think of a Goth teenager or a skunk or a coral snake. All of those have the black, the red, the yellow and particularly even black. It advertises throughout nature and in general lots of animals recognize it, and if they don’t at first, they learn it quickly when those colors are paired together, the aposematic colors, it means “don’t eat me, I taste bad, I have chemicals, or I’m venomous,” and so the firefly truly is.

Most of the ones we’d looked, the species that are little bags of defensive chemicals, which prevents most birds, most reptiles from eating them. There are some exceptions and so the mimic bugs out there, and there are lots of them. Every year I see different ones. They’re all pretending to be somebody else.

Q. [Laughter.]

A. Some of them are also chemically protected yet others are not, but they are trying to pretend to be. So they use those same black, yellow, and red colors, and it’s throughout nature, so if people start looking, it’s sort of a fun thing. But the lightning bugs in general are filled with interesting chemicals, and it does help them survive to adulthood to be able to lay their eggs to start the next generation—which is the whole point.

Q. I asked about how many species there were in North America. Are they elsewhere in the world, are they around the globe?

A. They are. They are worldwide, except for Antarctica. That’s the only place, supposedly. And we as a firefly community, which is quite small, but boy we have fun when we get together. We meet every three years in a different hemisphere to discuss all the latest research and discuss the problems we all see happening and to really get to know each other.

And it’s fascinating with the miracle of Internet, many, many papers have come out of that with people writing, with co-authors they either never met or just met once at one of the symposiums, but it’s interesting to me the things that we worry about here, everyone is worrying about.

Whether you’re in Japan or Borneo or Thailand or Portugal or Brazil: Everyone is concerned of habitat fragmentation, habitat destruction, light pollution particularly for fireflies is a big one, and environmental toxins—the pesticides, herbicides, and all that. It really doesn’t matter how remote you get. Everyone is worrying about the same thing.

Q. Light pollution is something that I’m very interested in. I grew up in New York city. I was born in, one of the boroughs in New York City. Light was … I didn’t know the real dark even when I was young and you know what I mean. It was the age where our “progress” as a civilization we were lighting, and lighting, and lighting, and having close-by neighbors and stuff like that.

The last 10 years, I’ve lived in a rural place where it’s very, very dark, and we don’t have any street lamps or anything like that for a long distance. It’s very different what goes on at night because of that, and I’ve been thinking a lot about light pollution, so of course this would affect these creatures of the night. What do fireflies do during the day, by the way? The adults, where are they?

A. Well there are some that are day-active, the diurnal ones, and for the most part, these are the ones that no longer have lanterns. They’ve lost them through evolution. The ones that flash at night, they just hang out, and you rarely see them. Even with populations like the famous ones in the Smokies that has thousands and thousands each night.

You would think during the day you’d see them hanging on the bottoms of leaves and things and you really don’t. So they go to some sort of cool hidden safe place and we don’t know where that is. You run into some of them—the park bathroom walls. Actually I go there to do census, I can tell which species are out. I’ll go to those cooled moist bathroom. The old-timey block walls, and go there to check to see which species are currently coming out because I can find them there. Generally, you don’t see them much during the day.

Q. I hate to even ask how they light up because in the book I know you say it’s complicated.

A. [Laughter.]

Q. And so don’t try to explain the chemistry of that, necessarily, as much as what is the light about; what’s it for? Why do they do it?

A. There again, you get a bunch of firefly people together and they’ll have 50 different reasons, and we do think it’s actually multiple reasons. In the world now, it’s primarily for mating, and it’s a love song that the male sings through light to try to attract the female to answer back. The females are usually hidden down in the leaves, and he’s the one you see at night.

When you’re a little girl chasing them in your yard or your grandmother’s yard, it’s the males that fly around. They’re flashy, they want to be seen, and each species has its own specific little pattern it does that only his female will recognize. And when one of them catches the female’s eyes, she will bend her little abdomen and she usually just has a little light, a little tiny lantern, and she will aim it at the male she wants, and flash, and hopefully he sees her and lands, and they mate.

But that is where light pollution comes in, it’s devastating, because no firefly can compete against a glaring outdoor light. So it’s their song of love. Also the larvae also glow, they’re what we call the glow-worms, and they will glow periodically and it is considered that that is still aposematic. It is warning the frogs and the birds out there, “don’t eat me, I taste bad.” Yes, so it’s actually a multi-pronged.

They also will flash uncontrollably when they’re in a spiderweb. They are some spiders that eat them regardless of the chemicals. When fireflies are stressed, certain genera flash, and others go dark. It’s very specific on which species you’re looking at. The flashes are caused by chemistry and oxygen and ATP [adenosine triphosphate], and an intricate mechanism. But it’s something they’re born with—it’s amazing, and it’s cold light, it’s not hot light. [Above, larvae of different genera differ greatly in their appearance, though all larvae glow at least periodically. Left to right, larvae of Lucidota atra and Photuris.]

Q. No heat is generated.

A. Yes, no heat is generated. It’s pretty miraculous process when you think about it, but light pollution is something. So I ask people a very simple thing to do is turn out your lights when you’re in for the night. A lot of people feel like they have to have 30 floodlights on. We actually have a neighbor like that. It’s like: why do you want all these floodlights? The simple thing of just turning them off and shielding your lights—that’s a big deal particularly the outdoor light.

Q. It sounds like the flashing, that it’s like sky writing. It’s like a silent language, yes?

A. It is.

Q. You said each species speaks it a little bit differently, distinctively. In the front of the book, sort of a fold-out chart, is this amazing thing called male primary courtship flashes. It goes species by species, and it’s this chart.

A. Isn’t it pretty? [Laughter.]

Q. Each increment across the top of the grid, the horizontal axis I guess you would call that across the top is by second—by pulses of seconds. So it shows you if there’s the first six boxes and each has a pulse or a little dot in it, then you know it pulses every second, a total of six times. Or if there’s two dots in each of three one-second boxes, you know that’s the pattern. Really interesting, and the shape—all of it is just fascinating that they make these pictures.

A. Well, in your yard, and this is the way I began, too. First you go, “I want to find out what I have in my yard,” and you’ll be surprised you’ll have more than you originally think. But once you get good at your own little yard, what you have and initially—and you might have to catch a few and look at them up close.

But once you learn that flash, the flash patterns, you can survey a forest and go, well, that’s a such and such, and that’s a such and such, just simply by their flash pattern, which is always paired with temperature, by the way. The hotter it is, the faster everything goes.

But it is fun so don’t try to learn all of them at first. Just learn the one in your yard, and you will also find if you write it down, it will appear the same time and the same place every year,  because they’re habitat-specific. So it’s not as hard as it seems, and then once you’ve learned yours, you can go a little further to a local park or something, see if they have anything new. But you’ll get to where you’ll recognize that you’ve not seen that before, and that’s how you find the new ones.

Q. They’re neither a garden pest, but are they … they’re not a garden pest at all, but are they a beneficial insect in some way? Do they have a role? Are they the favorite food of someone else? Where do they fit in ecologically sort of into the web of life thing?

A. From the human perspective, they’re almost neutral, I guess. They bring a lot of intangibles of happiness and warmth and everybody likes looking at them.  I have a young man that’s going to propose to his lady love this summer and he’s been consulting with me for weeks on when is the best night to come to the Smokies to do a proposal [laughter], so they have those sort of benefits to man that you can’t really measure.

But their larvae are predators and live in the soil, and so those larvae eat lots of little tiny microscopic and small insects, all the way up to roaches. I’ve seen a larvae run down a living roach and catch it and eat it.

Q. Wow, that’s my last name; watch out there.

A. [Laughter.] They are part of the web of life, and so when we kill all the garden pests, you actually and directly are affecting them, because there’s not as much for the larvae to eat, and the larvae live, particularly up your way, up to two to three years. Down here, they’re more on the one-year cycle.

So they do eat things but they are not considered an agricultural pest. They don’t carry disease, and they eat little things in the soil. And the adults generally don’t eat at all with the exception of milkweed, which is sort of a new finding, and they do technically pollinate milkweed but they are not super-important pollinators and so they’re just a neutral happy little insect, which is one reason I like them. Nobody screams at me about them, and everyone seems to like them, and so they’re sort of a happy little insect. [Laughter.]

Q. I want to talk about you’ve mentioned the Smokies a couple of times. Is that sort of the American epicenter of firefly activity? What are some of the hotspots around the U.S.?

A. The hotspots, there are actually quite a few. It depends on what you’re looking for. The Smokies, by accident sort of, became very famous for one particular species called Photinus carolinus, and the males flash in synchrony with each other. They flash six times quickly, followed by six long seconds of dark, and then they all flash again, and then it’s dark again. It’s fabulous.

But what I like people to know this, they stretch from North Georgia all the way up the New York. They go up the Appalachians. They’re an Appalachian type of firefly, and they’re in certain elevations. They like the high montane river valleys and they like mature forest, and they’re found throughout. It does seem that the Great Smoky mountains is the epicenter for this species because the density is enormous in an area, Tennessee, and North Carolina, and the Appalachians.

I’ve seen them up there in Southern New York and Northern Pennsylvania and there are some nice displays, of that species there. But other than that species, the hottest spots that used to be were Northern Florida and Southern Georgia. There was a strip they call like the fertile crescent, that have 56 species just right there.

Q. Oh, my.

A. No one has done a survey recently. I’ve been down there and did see some pretty exciting things, but there is so much pesticide and agricultural pesticides have affected a lot of that unfortunately—spraying for mosquitoes, all that stuff is hard on them, and development, of course, Florida is so overdeveloped now.

And so it used to be the hotspot, but now it’s the Southeast has more species than, say you do in New York—but you have a lot of them.

You might have more individuals of the fewer types of species but I was actually amazed that there wasn’t that much difference between Tennessee and Northern Pennsylvania, New Jersey, and New York. A few species replace each other, and we do have a few Southern ones that you don’t have, but generally you have plenty and real variety.

Q. In the Middle West or the Pacific Northwest, they have fireflies, do they have a lot? Other areas of the country that have or not?

A. They do, but we need some firefly nerds to develop out there. There are some very obscure ones, they don’t do the brilliant flashing out there in the West. We have found some populations as far West as California and some up in Alberta that do flash, but they’re very isolated and you really have to look for them. But there are some fascinating members of the firefly family in the west, even in the deserts, the Mojave Desert. These odd places have these super specialized interesting fireflies but you won’t be able to sit in your lawn chair and watch them flash past you. You actually will have to look for them.

Q. The Midwest, is there in the middle of the country?

A. In the Midwest has quite a few, yes.

Q. O.K.

A. And in Texas, it’s like its own world. It has things that come up from Central America. It almost needs its own book.

Q. [Laughter.]

A. They have so many. But the Midwest has some fabulous displays, and sometimes they’ll reach huge numbers of one species. But then generally when you get toward the Rockies, everything sort of starts falling apart, and you get down to the little bitty isolated populations around springs or places, and unfortunately a lot of development.

The populations that existed 50 years ago often no longer exist, because of development. And as you go out west, to me, this is interesting. There are two types of females. Females with wings and females that never grow wings. As you go West, more and more of them have the females that never grow wings so they are very vulnerable to extinction. They only move a few meters their whole life. They can’t leave. And so you disturb habitat, and they’re usually gone. They can’t repopulate.

Q. Well, Lynn Frierson Faust, the book is great. It really woke me up so, thank you, thank you.

A. Well, thank you, Margaret, and I want you to figure out what you have in your yard and report back to me.

enter to win the firefly field guide

I’LL BUY A COPY of Lynn Frierson Faust’s “Fireflies, Glow-worms, and Lightning Bugs” for one lucky reader. All you have to do to enter is comment in the box at the very bottom of the page, answering this question:

Do the nights get dark enough where you live to enjoy the visual love songs of the fireflies, and do you see them there in summer, perhaps?

No answer, or feeling shy? Just say something like “count me in” and I will, but a reply is even better. I’ll pick a random winner after entries close at midnight Tuesday, May 22, 2018. Good luck to all; U.S. and Canada only.

prefer the podcast version of the show?

MY WEEKLY public-radio show, rated a “top-5 garden podcast” by “The Guardian” newspaper in the UK, began its ninth year in March 2018. In 2016, the show won three silver medals for excellence from the Garden Writers Association. It’s produced at Robin Hood Radio, the smallest NPR station in the nation. Listen locally in the Hudson Valley (NY)-Berkshires (MA)-Litchfield Hills (CT) Mondays at 8:30 AM Eastern, rerun at 8:30 Saturdays. Or play the May 14, 2018 show using the player near the top of this transcript. You can subscribe to all future editions on iTunes or Stitcher (and browse my archive of podcasts here).

(Photographs from Lynn Frierson Faust; used with permission.)

  1. Mike Z says:

    The meadows and forests of Indiana light up throughout the summer. My backyard puts on quite the show, but I had no idea there were so many species. I haven’t seen any variation in my yard species. Perhaps I haven’t been looking closely enough, though.

  2. Lisa - Ontario says:

    I love fireflies. When I was looking to buy my house I saw them across the street and I fell in love with my neighbourhood. I removed the grass in the backyard and it is all garden now, and some years it is like a magical fairy world. I have been looking for more information on fireflies, it is very hard to come by. I’m so glad that now there is a book.

  3. Beth Romich says:

    I have fireflies in my yard and behind me in the field, usually June, July. They are nothing like what I would see as a child in Rockland. Beautiful and I love to see them and point them out. I was so upset when a neighbor set up lights at driveway which break up the darkness! But thankfully I still get fireflies!

  4. Kay says:

    This podcast was a joy to listen to! Fireflies are such a common sight in my area and yet no one really knows much about them. It was so informative and surely peeked my interest. I think I will be buying my own copy of her book.
    Another bonus for me was to hear that someone else has an issue with the negative impact of lighting up the night. I live in a very agricultural area: the night is so quiet and beautiful except for the farms around us that find it necessary to mount big barn lights on every corner. I often wonder why we are so afraid of the dark and why more people aren’t up in arms about light pollution.

  5. Madeleine Swirsky says:

    I’ve only recently seen grand firefly light shows with hundreds or maybe thousands of simultaneous flashes in recent years. Nothing I know of has changed where I live. Or — it may be the screened in gazebo allowed me to stay out and see the action in an area of my 1/2 acre yard I normally didn’t view.

  6. Janine McCreery says:

    Yes, it gets dark enough in my yard to see the flashing, but I also enjoy going into the mountains to see the Blue Ghost fireflies. One day I hope to see the synchronous fireflies in the area.

  7. JoEllen says:

    As a milkweed planter I was thrilled to hear that fireflies both eat and pollinate milkweed. …and I love that they carry their headlight behind.

  8. Jill says:

    I always look forward to seeing lightning bugs here in Western New York, but now I want to see all the displays that I’ve been missing around the country!

  9. Janine H. Petro says:

    Viewing fireflies in our Indiana, PA (home town of Jimmy Stewart) backyard is just one highlight of our summer. A firelfy tradition from the time I was little is to try to catch the first firefly I see of the season…then I promptly make a wish or say a prayer and let it go. Absolutely loved this podcast!

  10. Teresa says:

    Fireflies are my favorite!!!! When I lived in Japan, I used to see what I think is the larvae glowing in the dirt along the banks flanking the road when I walked my dog at night. I am always waiting to see my first firefly of the season this time of year, I can see them from my back yard all summer. I have a small mature forest in the valley beyond my yard, and can watch them flying even in the treetops. Please count me in, I would love to know more!!!

  11. Dianne Jenniges says:

    I live in a small town with street lights but I haven’t noticed the fireflies. I will have to take a look after dark

  12. Paula says:

    I love to watch fireflies here in Columbia county. And I carefully protect milkweed plants on my property–good to know it’s not just the butterflies that need them.

    As a youngster my husband would catch fireflies and release them at night in his bedroom so he could watch them flash. That would annoy his mother who had to round them up and set them free the next morning.

  13. Marla Rohwer says:

    Fireflies are abundant here in the Hudson Valley.
    I live on a pond and luckily the nights are quite dark.
    My childhood was filled with the magic of chasing fireflies
    during my Catskill summers. I
    I watch them now as I look for nighthawks over the pond or
    prowl around my garden.

  14. Carolyn Roof says:

    Fascinating. And, I just thought they would neat bugs that came out in late summer nights, something to put in a Mason jar, at least for a little while.

    Did you know that So. Ill. University researchers crossed lightning bugs with tobacco? It was to see if the chemical in the lightning bug would react to disease and early spot the source .

  15. Nicole L. says:

    Gratefully, we moved to a more rural location of Central Texas, and we have fireflies! I’d only ever witnessed their beauty a few years back, but my boys had never seen one until we moved here. Devices were forgotten, and for a little while, we all watched the magic, together.

  16. Jeanne DeFriese says:

    great article! Yes, there are fireflies where I live, in far south Austin, TX. Sometimes they are in large groups (large for here) about 4-5 ft above the ground, sometimes a solitary one will be up high, say 15-20 ft. I love them!

  17. Annie says:

    We live west of Portland Oregon. One evening a few years ago we saw fireflys in our neighbors willow tree. We watched for a long time as we had never seen fireflys west of Michigan where I grew up. The next morning the power company came to severely cut back the willow as it was a threat to the power lines. We have not seen the fireflys since.

  18. Florence says:

    We don’t see as many now as we did in years past (Killingworth, CT), but who knew there were so many species!! It looks like an interesting book.

  19. Kerstin DeRolf says:

    My husband and I love the fireflies this time of year – sadly, this year has been so strange we don’t seem to have any yet… :-(

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