Fireflies of Florida | Coast to Canopy Episode 4

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LISTEN: Fireflies of Florida | Coast to Canopy Episode 4

A few years ago, my family camped with a few other families at Suwannee River State Park. The sun was starting to set, and the fire at our group site was getting started when a fellow camper pulled me aside. “The fireflies on the trail are amazing right now.” I’d walked that trail several times over the years. It follows a spring run that sometimes runs dry, and sometimes flows voluminously. Each little hike was memorable in its own way, whether I was cooling down a heated eight-year old or exploring before other campers woke up.

As I walked to the Suwannee River and back, it grew progressively darker, and the firefly flashes glowed brighter. The fireflies made my memory of that walk burn brighter, as they have for other memories in Tallahassee or in wilder places. Fireflies have a way of adding a touch of magic to a spring or summer evening.

Part of that magic is the mystery of fireflies. Many of us only ever see the flash, and wouldn’t know the insect if it landed on our laps during daylight hours. Would knowing what they look like ruin the magic? I think not. And the more I’ve learned about them through the process of producing this podcast, the more I see that we still have much to learn about many firefly species.

My guest is Dave Almquist, Invertebrate Zoologist and Assistant Data Manager for the Florida Natural Areas Inventory (FNAI). FNAI tracks species of conservation concern in Florida, and that does include a couple firefly species. We last met Dave while helping him find new locations for the rare sandhills cellophane bee.

When I started research for this episode, I was most surprised by how many species of firefly we had in Florida, and how different they were from one another.

Coast to Canopy blog posts are curated transcripts. My notes appear in italics.

How many firefly species do we have in Florida?

Dave Almquist: There are more than 50, and possibly as many as 60 species in Florida.

Rob Diaz de Villegas: We were talking a bit before this when we were doing the pre-production – just in your neighborhood, how many species have you found?

Dave Almquist: I think I found seven or eight, although one of those is not a flashing firefly, which maybe we’ll get into later… But I think seven or eight in my little neighborhood in the middle of Tallahassee.

Here are a few fireflies Dave found in his neighborhood:

Are fireflies actually flies?

Dave Almquist: Well, fireflies, that are also called lightning bugs, are not flies nor true bugs. They’re actually beetles. And I am also, besides an entomologist, which is somebody who studies insects, I’m also a coleopterist, which is somebody who specializes in beetles, and fireflies are beetles.

For many years I pretty much ignored them, in part because I thought other people were taking care of researching them in Florida, and I figured I would concentrate on other things so I wouldn’t duplicate efforts. But then, a few years ago, I started getting interested in them and realized how little there was known about them. And I’ve been, chasing them ever since.

Rob Diaz de Villegas: What sparked your interest?

Dave Almquist: I think it was a blue ghost firefly that somebody told me about, up near Havana (Florida). And I quickly looked online and was like, there are no blue ghost fireflies here. They must not know what they’re talking about. But I went up there and sure enough, there were blue ghost fireflies up there. Or at least some kind of a ghost.

The jury’s still a little bit out on which species it is.

Anyway, my finding out that there was a species of beetle in Florida that I had no idea occurred in Florida that started my interest. And then I kept searching and finding new things. And that just spurred me on even further.

What does a firefly look like when it’s not flashing?

Dave Almquist: If you’re looking at them from the top, you won’t actually see their head. You’ll just see the edge of their thorax most of the time… If they’re just kind of sitting there during the daytime, you’ll see… their head come out from under that hood when they start moving around.

And the hood isn’t quite the right term, but that’s what it reminds me of, is sort of like a beetle hoodie.

Why do fireflies flash?

Dave Almquist: Most of what you see flashing, if you see fireflies anywhere, are males and they’re flying around flashing, trying to attract females. It’s sort of like a dating site where they’re putting themselves out there, and the females usually hunkered down right near the ground, or maybe perched a little bit up on some vegetation, depending on the species.

And they’re just kind of sitting there waiting. And they if they like what they see, they may give a little brief response, a flash letting the male know that, oh yeah, you look good. Come over here.

Unless you’re looking very, very hard, you’re not going to see the females.

According to Marc Branham at the University of Florida, the flashes also signal to predators that fireflies taste terrible.

Here’s a video Dave took of fireflies flashing with his drone.

Reading firefly flashes

One way to get to know firefly species without seeing the actual insects is to observe the way they flash.

1. Flash patterns

Dave Almquist: Different fireflies have different flash patterns. How long they flash, how long the interval is between flashes, sometimes the shape of the flash.

There are some that swoop up in a J shape when they flash. There’s a the ghost species, they fly just barely above the ground, and they don’t flash so much is put out like a continuous glow. It almost looks like a line of glowing. And then they stop.

There’s one that, to me, sort of reminds me of a 4th of July sparkler a little bit, because instead of just a flash or a double flash, it kind of sputters as it moves.

There are also different colors to an extent… They’re mainly green, but [some are] a little more towards maybe orangish. Almost some appear yellow and then some a little more towards blue.

Some of them are like almost instantaneous, whereas other ones are more drawn out. And then there’s the the ghost ones that are kind of ridiculously glowing.

2. Height

Dave Almquist: Another thing that’s characteristic is how high they flash.

Again, the ghost ones, they’re right near the ground there. There are some called treetop flashers, and they live up to their name where they are way out of reach, way in the treetops.

So the height is diagnostic per species to an extent. There is a species active in my backyard right now. That stays about maybe ten feet from the ground. Mostly a little bit lower, like around head height. Well, at least my head. And then there are other ones, that start off low, but they will end up way up in the trees.

And then there are other ones that only, only fly within a certain like, a certain height above the ground, within certain parameters.

3. Time

Dave Almquist: The time in relation to sunset that they flash can also be very diagnostic. The main species that’s active in my backyard right now starts just a little bit after sunset, and pretty much is done flashing about 15 or 20 minutes later.

So if you’re not exactly in that right spot at that right time looking for them, you’re never going to see it. There other similar species, you know, similar in their, habits, that start right at official sunset. Like, you could set your you could figure out what the sunset is by the first flash of them that you see, and they only flash for about 15 minutes.

And if you think about right at official sunset, it’s actually still relatively low light out. So they’re very hard to see unless you’re really staring straight at them.

Firefly larvae

Dave Almquist: Beetles have complete metamorphosis. And that’s just a fancy term for basically being like a butterfly, as far as they have a larval stage, which is basically a caterpillar.

They have an egg, then they have a larval stage, then they go into something basically like a cocoon, and then they come out as an adult. And so the adults usually only live a couple of weeks.

I don’t want to make any unqualified statements about fireflies, because anytime you say fireflies do this, there’s one that doesn’t do that. And anytime you say fireflies don’t do this, there’s one that does.

But, in general, I think most of the adults only live a couple of weeks or so. The larvae, which is the sort of caterpillar stage for them, they can live, for some species, up to two years. And what they do is crawl around on the ground under leaf litter, down on the dirt, up on trees.

And they kind of look to me like a pangolin or maybe an armadillo. But if you know what a pangolin looks like, that’s what a lot of them look like to me. And they are predatory. Most of them are predatory on snails and slugs and so forth.

Most of the adults don’t even eat at all. But then there are other adults that like a little bit of nectar and pollen. And then there are other adults, in genus Photuris that have been called femme fatales. They mimic the flashes of other firefly species and draw in the males that think that it’s a female of their species, and they actually eat the males.

Fireflies in the Wild

Dave Almquist: I’m pretty proud of having found as many species as I have within Tallahassee in my neighborhood. I think only one of those was maybe somewhat uncommon. But yes, if there are species that we know relatively little about, they definitely occur in kind of more rare habitats, and more pristine habitats, basically.

Pointy-lobed firefly (Photinus acuminatus)

Dave Almquist: There’s one that I think it’s called the pointy lobed firefly. It seems from the little knowledge that we have that it seems to like a marshy area, maybe a cypress swampy area. Right next to some very dry sandhill type of habitat.

We are we are tracking that species, which means we try to gather information about it and gather locations for it and things like that, but it hasn’t been seen in decades. So I would love to find that. But that’s one example.

Florida intertidal firefly (Micronaspis floridana)

Dave Almquist: There’s the Florida intertidal firefly, Micronaspis floridana. It’s only found in salt marsh/ mangrove habitats, and only in peninsular Florida. Although, I really want to go down and look in some of the salt marshes down near Saint Mark’s, because I wonder if maybe it’s hiding out there just because nobody’s looked for it.

Ant-loving scrub firefly (Pleotomodes needhami)

Dave Almquist: There’s also an ant-loving scrub firefly, which the females do not fly.

Their wings and their elytra. The elytra for beetles are basically what you think of as sort of the shell. But they kind of split that apart, and then their flying wings come out from under it. So the ant loving scrub firefly, which is Pleotomodes needhami, the females are flightless and they live in ant nests and they come out at night and glow.

The males, which do fly, come by and they glow also, they don’t really flash. They only live in scrub habitat in the peninsula. And scrub habitat is very, very dry and sandy. So, [for most firefly species] we’re talking about leaf litter and habitats and wetlands and stuff like that. This is the opposite end of the spectrum where, well… we need some humidity and we don’t have leaf litter. It’s very sandy. So we’re going to go hang out in an ant nest.

Everglades Browning Firefly (Photuris floridana/ Photuris brunnipennis ssp. floridana)

Dave Almquist: The Everglades Browning Firefly, which is for Photuris floridana. That’s another one that has not been seen in decades. And the ant loving scrub firefly that I was talking about before are both endemic. There are probably other endemics that I just don’t have on my radar right now.

Florida scrub dark firefly (Lucidota luteicollis)

Dave Almquist: There’s a Florida scrub dark firefly, and it’s diurnal, and the flightless females live underground. And people think that the females use pheromones to attract the males, rather than using the light, which is somewhat interesting.

The winter firefly

Dave Almquist: It’s called the winter firefly, surprisingly enough, because it comes out in winter time. As far as I know, there are only a couple of records for that, or possibly a related undescribed species in Florida. But, well north of Florida, they actually do come out in winter time in places that snow. Lynn Faust, who wrote Fireflies, Glow Worms and Lightning Bugs, basically wrote the book on fireflies from North America. She had documented four individuals that crawl up a tree trunk.

People actually find them in cracks in tree bark, and they’re visible [in the winter]. Anyway, she found some four of them, and they survive down to -13°F. Now, that’s not below freezing, that’s below zero. And a few days later, when it warmed up a little bit, they crawled away and they were perfectly fine.

Not very many insects could survive that. I know I couldn’t survive that, but I just thought that was interesting.

Rob Diaz de Villegas: That’s found in Florida?

Dave Almquist: There are a couple of records for at least that genus, as we were talking about before. Can’t quite say definitely. And I believe there are at least a couple of records even on iNaturalist for that species or maybe, [an] described one. Anyway, if, if people want to go out, staring at tree trunks in like late fall to really early spring, you might find one.

I’ve tried, I haven’t yet, but I haven’t been in that many habitats. They apparently like large trees with cracks in the bark. And they also like a somewhat spread out, not a completely closed canopy above shading everything, but not totally open like a field with just a couple of trees. They want a decent number of trees around, but still some light getting through and stuff like that.

I’ve heard, that at night is the easiest way to find them, even though they do not flash. And the way to find them is using a headlamp. They apparently shine, like, not fluorescence or anything. But they apparently are pretty obvious with a headlamp at night.

Non-flashing fireflies

Dave Almquist: There are species that do not flash at all, and they actually come out during the daytime. One is called Pyropyga minuta, or the flower elf. Another one is called the woodland Lucy or Lucidota atra. And to me, the coolest one is called the tropic traveler. It’s Tenaspis angularis. And it’s somewhat of an odd looking firefly because it’s very, very wide. More of like an oval shape than elongated.

I found one in my yard years ago, took a cellphone picture of it and… I knew it was a firefly, but didn’t quite know what which one it was. Anyway, I found out it was relatively rarely found, and I showed the picture to my son Lukas, who was like nine years old. A couple days later he came home from school and he had this cup in his hand.

He didn’t tell me what it was and then opened it up and I’m looking in and he found that same species. I’d only seen it once, and I’d done a lot of looking around in Florida. I’d only seen it once. And he found it at his school in Tallahassee.

I thought that was pretty cool. The specimen that he collected me ended up giving to Marc Branham at University of Florida, and he ended up using it for DNA analysis to figure out how far flies are related to each other.

Helping Firefly Larvae in Your Yard

Dave Almquist: I would say that if you want to promote fireflies in your yard, that the number one thing would be don’t use pesticides all over your yard, which means don’t spread stuff around in your grass to kill grubs and stuff. Because if you’re spreading around things that are killing grubs, it’s probably going to kill firefly larvae.

If you were spraying or having your yard sprayed for mosquitoes, they’re going to spray right after dark. And that’s right when a lot of the fireflies come up. So to me, that’s the number one thing.

Leaf litter is somewhat important. But they could probably find some leaf litter around the edges in your yard. If you don’t want your lawn to have a whole bunch of leaves in it, just push some of the leaves off to the side and they’ll find them.

Light pollution is somewhat of an issue… again, I’ve found about seven species of fireflies in my neighborhood in Tallahassee. Obviously, there are streetlights all over the place. And I’ve watched them fly right under streetlights that were on. So I don’t know how important light pollution is to them, but I think maybe more to the later flying species.

And it’s a good idea to decrease light pollution in your house, anyway, because you’re pretty much drawing insects to your house, and then they’re going to try to crawl into your house.

To me, the best way to do that is if you have a light that’s on all night long that you don’t want to have on a motion sensor, see if you can get a yellow light. Because they attract many less insects. But motion sensor lights are the best bet because they’re not on all night. You still have the security of them coming on when they’re needed.

A video provided by Dave Almquist of fireflies flashing.

Photographing/ recording video of firefly flashes

Dave Almquist: It depends, because I was just talking about ones that come out very early. There are other species that do not come out until about an hour after official sunset, when it’s pretty much truly dark out. And if there is no real moon and it’s one of those species, I’ve had a very difficult time getting video on my phone of their flashes unless I could get relatively close to them.

The ones that come out more around dusk when there’s still a little more ambient light and stuff – those I can use my phone to record their flash patterns

If you have your location set up a setting on in your phone, then you know exactly where you took that video later on. And then you can very carefully go through the video and go, okay, this one flashes very briefly, 1 to 2 seconds apart and looks like it was about six feet above the ground. And then you have a wealth of information to help you identify that firefly.

Everybody’s phone is different. And I don’t want to get into a tutorial on, on phone videos, but for any video, fireflies, if you can find settings in your phone to, increase the resolution as well as, the frames per second, those things help a lot in taking Firefly videos.

Getting good photos of fireflies

Dave Almquist: Usually what I do with fireflies is if I see one, I try to track that firefly with my eyes, watching and getting an idea of its flash pattern is like… [then] I get a video of that flash of that specific firefly, and then try to net.

And you don’t have to use the net depending on the species, some species I have not been able to catch even with a ten foot long net that I made. But other species you can catch with your hand, just as you may remember doing as a kid, and even some of the very interesting species.

Whatever way you catch them, the best way I found to get a picture of them is to put them in a little Ziploc sandwich bag and get most of the air out, but not all of it. And don’t worry about them suffocating in the minute you’re taking pictures, because it’s kind of like you being under a really heavy blanket for a couple of minutes.

Then try to get photographs of the topside or dorsal and also the bottom side or ventral view. Because there are diagnostic characters on the underside for some species.

Again, I don’t want to get too far into phone settings, but, if you can increase the resolution of the pictures that you were taking, that will allow you to crop to just the insect and have more detail, if you can.

When I put one in a plastic bag, I usually have a headlamp on. So that way my hands are free. It’s a little difficult to shine your headlamp on the firefly and take a picture with your cell phone and not have the shadow of the cell phone or the shine from the bag obscuring, the specimen that you’re trying to get pictures of.