Author Archives: Sara Lewis

Next up: Fall glow-worm extravaganza

Autumn happens to be quite an exciting time for fireflies. I get it – you probably can’t imagine fireflies beyond summer.  And that is when adult get all reproductive and stuff. But there’s cryptic chapter in the firefly’s life story, and it’s starting right now.

Firefly Life Cycle.png

Once mated, the female firefly will produce 30-100 eggs, laying them one-by-one in some moist dirt or moss. After a few weeks, these eggs hatch out into tiny larvae that immediately burrow down underground. Though adult fireflies only live a few weeks, their progeny will spend up to two years hanging out underground.

Larval Jaws

photo by Melvyn Yeo (Flickr)

Baby fireflies happen to be voracious predators. They’re constantly on the hunt for earthworms, snails, and any other soft-bodied prey. They attack creatures that are much bigger than themselves. How do they manage this? First, they use their sharp, sickle-shaped jaws to inject the prey with paralyzing neurotoxins. Next, they secrete digestive enzymes to liquify their prey, then they slurp it up. Earthworm smoothie, anyone?

When they’re disturbed, larval fireflies glow from two tiny lanterns located at the tip of their abdomen. All firefly larvae can light up, across 2000+ species, even when the corresponding adults cannot. So we think fireflies’ light-producing talent first evolved because it gave these juveniles some advantage.

But … what’s the point of these juveniles being so conspicuous?

We know that fireflies contain nasty-tasting chemicals that help them avoid getting eaten (see earlier post). Lots of poisonous creatures use bright coloration to warn off potential predators. Yet firefly larvae are mainly active at night or underground, where having bright colors would be futile. But a flash in the darkness would certainly do the trick – like a neon sign, it  blazes out “I’m toxic – stay away!”

So get ready to watch for firefly larvae crawling along roadsides and wooded paths, glowing dimly. Often overlooked, these juveniles should rightly be celebrated as the original inventors of fireflies’ magical lights.

pageofbats life cycle illustration

Illustration by pageofbats (Flickr)

Advertisements

What Twitter taught me about #fireflies

Over the past year, I’ve learned a lot about Twitter hashtags. For instance:

#firefly will usher you directly into the cult kingdom of the TV series Firefly, a sci-fi  classic billed by its creator as “nine people looking into the blackness of space and seeing nine different things.” firefly TVThe story centers on the crew of Serenity, a Firefly-class starship (when it took off, the ship’s tail section lit up). Premiered on Fox in 2002, the show featured a smart script, terrific ensemble acting, heartthrob Nathan Fillion, and a great theme song. In spite of all this, and to the eternal dismay of its many loyal fans, the show went extinct after just a single season. But on Twitter, it lives on.

Meanwhile, #fireflies yields an endless stream of tweets and Youtube remixes posted by fans of the song “Fireflies” by Owl City. Topping the US and Canadian charts in 2009, this song ties together insomnia, fireflies and summer.  Most frequently tweeted are these lyrics: Continue reading

Please don’t eat the fireflies!

Recently I’ve learned via Twitter that lots of cats (dogs, too) enjoy chasing after fireflies. But please don’t let your pets eat the fireflies! This is for their own sake, not for the fireflies.

cat comic

(Image: catandcatcomic.com)

Living in a world full of insect-eating predators, fireflies have evolved potent defenses to protect themselves. Firefly blood carries a bitter-tasting and toxic chemical called lucibufagin (lucifer = Latin for light bearer + Bufo = toads that produce similar chemicals).

 

lbg-photinus-e1499280681816.jpg

Firefly blood contains a potent toxin called LBG

Lucibufagin (often nicknamed LBG) makes a powerful poison because it is effective against almost any animal. It binds to and disables an enzyme, known as the sodium-potassium pump, that’s essential for all animal cells. This enzyme actively transports ions across cell membranes, generating an electrical potential that allows us to do really important things like think and move our muscles. To protect themselves, many plants and a few animals have converged on stocking similar toxins in their chemical arsenal.

Continue reading

Fireworks & Fireflies

From Joanne, in Wisconsin –

About 15 years ago we held a family reunion near a small lake in the Blue Ridge Mountains, near Saluda, NC.  It was around July 4th, so around the lake lots of people were setting off fireworks.  We were gathered by the lake near a wide grassy area that led right up to the base of the mountain. That night the fireflies appeared around dusk, just when the fireworks started. Although the fireworks were going off much higher up, we realized that down below the fireflies’ flashing was gradually getting synched up with the fireworks. As it got darker, the coordination seemed to increase so that every time a firework went off, the fireflies would light up, all pretty much at the same time.

It was a magical scene – a constellation of yellow-green flashes lighting up down near the ground, triggered by the dramatic firework explosions in the sky. And the fireflies earned much bigger “ooooohs!” than the fireworks! Only later did I learn that what we were seeing were probably the romantic signals of male Photinus carolinus fireflies, flashing together like one big mega-male to try to win the favor of their females.

Fourth-of-July-Weekend_Kerr-Lake

What’s for Dinner Tonight?

Every June, fireflies light up the Smoky Mountains with their exuberant courtship displays – sure, it all seems very romantic. But a few years ago I spent some weeks with colleagues studying the predators that take advantage of these dense breeding aggregations. We knew that certain insectivores – like birds and lizards – avoid eating fireflies because they’re toxic. So we didn’t expect to find many predators enjoying this luminous feast. Little did we realize how gore-filled that summer would turn out to be!*

Figure 1 from Lewis et al. 2012

* You can read our Dark Side paper  here: Lewis, S.M., L. Faust, and R. De Cock. 2012.  The Dark Side of the Light Show: Predators of Fireflies in Great Smoky Mountains. Psyche, 634027.

Continue reading

What’s good firefly habitat?

People often ask me this excellent question. Yet it doesn’t have a quick or easy answer. One reason is that different species live in different habitats. For instance, the salt marsh firefly Micronaspis floridana is restricted to intertidal regions along the Florida coast.  Another reason is that certain things matter to adult fireflies, whereas different things matter to the juveniles.

Micronaspis floridana

Some species have specialized habitat requirements (photo by Drew Fulton)

For adult fireflies, what’s most important is finding a dark place for their courtship displays. Artificial lights – streetlamps, outdoor security lights, even car headlights – can disrupt firefly courtship conversations.  Such bright backgrounds make it difficult for fireflies to see each other’s courtship signals. Another desirable habitat feature for adult females is easy access to suitable egg-laying sites, like moss, moist soil, or decaying wood.

Continue reading

Gratitude: Finding fireflies & friendship in Japan

For the most part, my friends politely tolerate my firefly obsession. Some even share it, for which I feel quite fortunate. But I am eternally grateful to one particular friend and kindred spirit, Hiromi Hirata. Smart, beautiful, and energetic, she has guided, accompanied, and translated for me as I’ve tried to learn about Japanese fireflies.

Toyko Firefly Breeding Institute

Visiting Tokyo’s Firefly Breeding Institute with my dear friend Hiromi Hirata and the director, Dr. Norio Abe

Some years ago, Hiromi  brought me to visit Tokyo’s Institute for Ecosystem & Firefly Breeding, a nondescript building hidden away in Itabashi-ku. There we met the crazed yet charming director, Dr. Noria Abe, who  spends months patiently raising thousands of  Genji fireflies through their entire life cycle. When they finally become adults, Abe-san releases his newly-hatched fireflies into a greenhouse where he’s constructed a complete indoor firefly habitat (really, a stream runs through it). Every June, for just a few nights, he opens wide the Institute’s door and invites the public to come experience the spectacular lightshow.

Tokyo Intitute for Firefly Breeding

The indoor light show in Itabashi-ward (photo by Norio Abe)

And Hiromi brought me to see the Insectarium at Tokyo’s Tamu Zoo. There, I  got to see first-hand how enthusiastically Japanese kids embrace insects!

One May we traveled together to Moriyama, a once-famous tourist destination for firefly watching. Situated on the picturesque shores of Lake Biwa, Moriyama still hosts an annual Firefly Festival (ホタるまつ). But, as described in an earlier post, by the early 20th century Moriyama’s firefly populations began to dwindle. What on earth became of all of Moriyama’s fireflies?

The surprising answer was revealed during a visit that Hiromi arranged to Moriyama’s Institute of Firefly’s Woods. This tiny museum houses a veritable treasure trove of primary sources explaining the history of Moriyama’s fireflies. With typical foresight, Hiromi also arranged for us to meet the director, Mr. Michio Furukawa. While Mr. Furukawa narrated our guided tour, Hiromi’s husband, Dr. Yukio Hirata, kindly translated.

I won’t retell the fascinating story here (it’s a powerful cautionary tale); if you’re interested, you can read about Moriyama’s fireflies in For the Sake of Their Glow. Instead, here I’d like to share some photographs from Moriyama, and to express my deepest gratitude to Hiromi & Yukio Hirata, my wonderful friends who made this trip possible!