Fireflies

Alex Re (00:00): Hello, welcome to On Wildlife. I'm your host Alex Re. On this podcast, we bring the wild to you. We take you on a journey into the life of a different animal every week, and I guarantee you, you're going to come out of here knowing more about your favorite animal than you did before this week. We're discussing an insect that often raises feelings of summer nostalgia. You probably have memories chasing these animals in the night. They can create some amazing spectacles because of their bioluminescence, and they're also important to the ecosystems that they're a part of. So take a look outside tonight because we're talking about fireflies.

(00:56): There are over 2000 species of fireflies and they can be found on every continent in the world except for Antarctica. They're most abundant in temperate areas with warmer climates, and they also love areas that are humid. You can find them near most bodies of fresh water as well as in forests, fields, and grasslands. Now, when I was growing up, I called them fireflies, but they go by many other different names like lightning bugs, glow flies, and moon bugs among many others. And of course, these names all come from the fact that they create their own source of light, a process called bioluminescence. This is one of the most amazing processes in the animal kingdom, but we'll talk about it later on in the episode. And the name Firefly can be pretty misleading because they're not technically flies. They're actually a type of beetle belonging to the lamper day family.

(01:52): Most firefly species only grow to be about an inch long, which is roughly the same size as a paperclip. The largest species is known as the lamp gerra. The females are larger than the males and they can grow to be around the size of your palm. If you live in North America, the species of firefly that you're used to seeing is most likely the common Eastern firefly. It has an orange head and black wings that have a yellow outline. These wings cover the abdomen, and if you look at the different species of firefly, many have very similar characteristics to the one I just described. Like all insects, fireflies have different lifecycles and their lifecycle determines what they eat as larva. They eat worms and slugs. The larva injects its prey with a numbing fluid, which turns it into a slurp liquid that they can eat.

(02:47): That's pretty disturbing. But once they become adults, their diet completely changes. As adults, fireflies don't really eat other animals. Their main source of food is pollen and nectar. Some species won't eat at all as adults. They also have to worry about getting eaten by other animals, and they have some defense mechanisms to ward them off. If they feel threatened, they'll secrete drops of blood through a process known as reflex bleeding. Their blood contains chemicals that taste bitter and are even poisonous to some animals. As a result, many species have evolved to avoid eating fireflies, especially bats. However, this doesn't mean that they have no natural predators. There are certain bird reptile and amphibian species that are able to eat them without being poisoned by now. I'm sure you're wondering about the defining characteristic of the firefly, their bioluminescence, and we'll talk about that right after the break. The science word that I want to tell you about today is telomere. Telomeres are basically end pieces of chromosomes that don't have important information on them. When D N A copies itself, the telomeres get shorter and shorter, and this protects the actual important information that D n A has.

(04:25): Okay, we're back time to talk about the light that fireflies make. And they mainly do this to find mates. Most fireflies are nocturnal and they use the darkness to their advantage because that's when their light can really be seen. But they don't just turn this light on and off randomly. Each species of firefly has its own unique light pattern. Some make a J shape in the air with their light and some do a series of quick flashes, pause, and then do that same series again. In certain areas, synchronous fireflies will light up in unison with each other. It's really amazing to see, and it kind of looks like a light show. And some species glow more yellow while others glow more green. But how do they make this light in their abdomen? They have a specialized organ that produces it called the lantern. When fireflies breathe in oxygen, special enzymes called luciferase in their lantern, react with Lucifer to produce light with practically no heat because there isn't really any heat produced from this process.

(05:33): It's called cold light and firefly light is the most efficient form of light in the world. 100% of their energy is emitted as light, whereas an iridescent light bulb amidst 10% of its energy as light and 90% just as heat. And the crazy part is we still don't really know how they're able to turn the light on and off. At will, in some cases, even firefly eggs and larva illuminate as well, they'll start to glow if they're touched by something. The way that their mating ritual usually works is that the male flies around at night flashing its light in a specific pattern. The female will wait in a safe location like a tree or a bush. If she sees a male that she likes, she'll send out her own light signal for him to meet her. But not every firefly glows in some species, only one sex, either the male or the female glows.

(06:29): But this usually isn't the case. And not only that, but some firefly species don't glow at all. Instead, they use chemical signals called pheromones to attract a mate. If you've ever seen a firefly during the day, chances are that it was one of those species. In species like the European glowworm, which is a type of firefly, the female can't fly and the male can. The female still produces light to attract a mate. Though not all fireflies use their powers of bioluminescence for good. As is the case with the genus of fireflies called Urus. Remember when I said adult fireflies like to eat nectar and pollen? Well, not these guys. They like to eat other species of firefly. This firefly actually mimics the light that a female belonging to a similar species called fontina would make. This attracts the males of that species, which they will then eat, but eating them serves a purpose beyond just for food.

(07:31): Preying on male fireflies of other species allows them to acquire the toxins of their prey. The female puts this over her eggs as a chemical defense against predators. These types of fireflies have also been known to sneak onto spiderwebs to steal their prey. This behavior is known in the animal kingdom. As klepto parasitism, firefly larvae develop underground and they don't emerge to the surface until adulthood. The larvae are flat with a 10 segment abdomen. The head is small with curved mandibles, they'll usually stay underground as larvae for a year or two. After this, they then mature into pupa for three weeks and then to adults for an additional three to four weeks. Most adult fireflies live long enough only to mate and lay eggs, which is why some individuals have been observed to not eat during this stage of their life. Okay, we're going to take our last break, and when we get back, we'll talk about some of the ways that fireflies sense the environment around them. Time for today's trivia question. What is the largest ocean in the world? A Pacific Ocean, B Atlantic Ocean, C Indian Ocean, or D Arctic Ocean. The answer is A the Pacific Ocean. It's over 63 million square miles across.

(09:25): All right, welcome back. Fireflies need some way to detect the light that they emit and they have pretty good eyesight that helps them see other individual's signals. They actually have different types of eyes in different stages of their lifecycle. When they're larva, they have simple eyes with no retina, and when they become adults, they have compound eyes that are a little bit more complex. This makes sense because their eyesight is important when they need to start looking for mates. Part of the reason we know that their eyesight is important for detecting the light that they emit is found in their fossil record. Throughout the firefly's evolution, scientists have found that as their lantern, which is their light organ increased in size, their eyes have increased in size as well. Their antennas, on the other hand, have gotten smaller over time. The antennas are there to help detect things through touch and smell.

(10:21): While fireflies mainly shine their light to communicate with potential mates, they also use it to defend themselves. Scientists believe that when a firefly flashes its light, it's the species way of letting a potential predator know that they might be toxic, so predators will know to stay away from them. Not only are fireflies amazing to look at on hot summer nights, but they're also important to the environments that they live in. They're integral to keeping the ecosystem in balance because they're both predators as larvae and prey species. In their larval stage, they eat large amounts of food that is then stored for their adult stage. All of the organisms that they eat are therefore kept in check. For example, in Asia, there's an invasive snail species called the apple snail. They've been eating and destroying farmers'. Rice fields and firefly larvae are currently being explored as a possible way to control those snail populations.

(11:20): And when fireflies become adults, we learn that they eat pollen and nectar because they need to get this from flowers. We know that they're actually pollinators. Fireflies are also effective indicator species for their environment. They're extremely sensitive to environmental conditions and can only thrive in habitats with good water quality. If fireflies are present in an area, this lets us know that the water quality is decent, as well as that the overall ecosystem is relatively healthy. Unfortunately, firefly species are in decline due to habitat loss as well as some other reasons. Fireflies live and breed in open fields, meadows, and forests. These ecosystems are being cut down and destroyed so that we can build new houses and cities. But something that you might not think about is light pollution. Fireflies depend on their bioluminescence to find a mate. The lights from our buildings and street lamps can interfere with firefly mating.

(12:21): This causes a decrease in their population. There are ways to help specifically with this problem. First, try to get rid of any lights in or near your house that you don't need. Next, make sure you either turn off lights when they're not being used, or have motion sensors that will turn off the lights if no one's around. And lastly, you can buy red l e d lights instead of the standard white lights. These red lights attract less insects. Doing all of this is really important because in the US and Canada, 11% of firefly species are close to extinction, including the Southwest Spring Firefly and the Bethany Beach Firefly. If you want to help fireflies, you should also check out the Zeri Society, the I U C N, Firefly Specialist Group and firefly.org. Thank you so much for coming on this adventure with me. As we explored the world of fireflies, you can find the sources that we used for this podcast and links to organizations that we referenced@onwildlife.org. You can also email us with any questions at On Wildlife dot podcast@gmail.com, and you could follow us on Instagram at On Wildlife, or on TikTok at wildlife. Don't forget to tune in next Wednesday for another awesome episode, and that's On Wildlife

Jess Avellino (13:52): You've Been listening to On Wildlife with Alex Re. On Wildlife provides general educational information on various topics as a public service, which should not be construed as professional financial, real estate, tax, or legal advice. These are our personal opinions only. Please refer to our full disclaimer policy on our website for full details.