Tag Archives: life cycle

Pyractomena Strangeness #3

The previous episode left our Pyractomena larva hanging  – literally – doing some aerial pupation, very unusual behavior for a firefly! Forsaking the amphibious wanderings of its snail-eating childhood, the pupa now hangs quietly. But inside, a maelstrom of cellular reorganization and growth is transforming its larval body. In just a few weeks, it will emerge as an adult firefly. At this next stage, our Pyractomena will have only one thing on its mind: sex. And yup – you guessed it: Pyractomena fireflies have strange sexual habits, too!

Most male lightningbugs fly & flash to win females. But after racing to emerge early, Pyractomena borealis males forcibly mate with their child brides! Continue reading

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Pyractomena Strangeness #2

We’ve already heard (previous post) about the weird hunting habits of Pyractomena larvae – they’re amphibious.  So let’s continue our Pyractomena tour, moving along to consider another strange behavior: they pupate en plein air!

Once they’re ready to metamorphose into adult fireflies, the larvae of most North American lightningbugs seek safety underground. Immobile, they huddle for weeks in soil chambers, finally emerging to light up our skies as adult fireflies. But no cold dark cellars for Pyractomena fireflies! Instead, these strange fireflies climb up onto vegetation to undertake a feat known as aerial pupation.

Pyr borealis pupation

Aerial pupation (photos from Faust 2012)

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Stranger Things – The Firefly Version

If you’ve been paying some attention, you probably already know that here in North America, we’ve got several different kinds of lightningbug fireflies. Those in the genera Photinus and Photuris are common and relatively well-studied. But the Pyractomena lightningbugs –  also pretty common – are a black box. We know so little about them! And more’s the pity because Pyractomena have a pretty bizarre lifestyle, making them quite a bit different from our other fireflies.

NAmerican Lightningbugs

Three North American lightningbugs, belonging to Photinus, Photuris & Pyractomena( L to R)

So here’s the first taste of Pyractomena strangeness: these amphibious larvae are snail-eaters! Continue reading

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)

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.

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Texas Glimpses Some Late-Season Wonder

In most years, Texas fireflies have largely faded out by August. But this year, a second wave of fireflies has washed across central Texas during mid-September. What’s going on?

Last spring, warm & wet weather conditions produced a bumper crop of emerging adult fireflies (reported here). And similar weather conditions this fall have apparently created a repeat performance (reported here & tweets below).

fireflies-texas-sept-tweets

Sept 2016 sparked a firefly Twitterstorm from Austin

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About Those Firefly Babies…

Everyone loves fireflies and everyone loves babies, so it sounds like baby fireflies would be extra cute, right? But….

They.are.not.cute.

what they eat

Baby fireflies are voracious predators

Baby fireflies are ruthless carnivores dedicated to gluttony and growth. During their juvenile stage, most fireflies live in soil and rotting wood, where they prey upon earthworms, snails, and other soft-bodied creatures.

For the past several weeks, I’ve kept busy rearing 20 Lucidota firefly larvae. Just 5 weeks after they hatched out from eggs, my baby fireflies are growing fast. But I have to admit, watching them eat is getting scary! If you’ve seen Stranger Things, maybe you’ll know what I mean.

At rest, these babies huddle together. When I give them an earthworm they quickly gang up on it. This gregarious feeding habit lets them take down prey  much, much bigger than themselves. Using their sickle-shaped jaws, they inject the worm with paralyzing neurotoxins. Then, while it’s still alive, they cut it up it into pieces. Over the next 24 hours, they line up like suckling piglets to suck up their liquified prey.  Yum – nice fresh earthworm smoothie, anyone?

Anyway, each night before I go to bed, I now check to make sure my baby fireflies are securely inside their containers. So sweet dreams!