On March 23rd Indiana became the fourth U.S. state to name a firefly species as their official state insect: Pyractomena angulata. Also called Say’s firefly, this species has a special connection to the state because it was first described by Indiana entomologist Thomas Say.
Pyractomena angulata (drawing by Arwin Provonsha) was discovered by Thomas Say in 1824
The official designation of Say’s firefly as Indiana’s first-ever state insect represents a heart-warming win, not just for fireflies, but also for the former 2nd-grade students at Cumberland Elementary School in West Lafayette. Beginning in 2014, they started lobbying for this action, mounting a letter-writing campaign and even a Facebook page. Working together with teachers, scientists, and legislators, the students managed to gain bipartisan support and earlier this month watched as the bill was signed by Governor Eric Holcomb.
The Firefly Flag (left), poem, and drawing by students from the Cumberland Elementary School (image from Xerces Society blog).
With its glittering presence, Pyractomena angulata just might be my favorite firefly – always gives me a thrill to watch these high-flying males rise and fall as they emit their distinctive long-lasting (~ 1 second) orange flicker. It’s also one of North America’s most widespread fireflies, occurring east of the Mississippi from Florida all the way north into Canada.
This species becomes active after dark beginning sometime in May in the southern U.S., June and July in northern regions. So even if you don’t live in Indiana, keep your eyes peeled for them this summer!
Synchronous fireflies certainly highlight Earth’s natural magic, yet such cooperative behavior presents quite a thorny scientific paradox!
We do know how some fireflies manage to synchronize their flashing, thanks to work done in the 1960’s by John & Elisabeth Buck (previous post). For instance, male Pteroptyx fireflies in southeast Asia can reset their internal timekeeper whenever they see a neighbor’s flash. Inspired by Steve Strogatz’s book, Sync, Nick Case made a spectacular simulation to illustrate how this works – I’ve played with it for hours, and you can, too!
Synchronous fireflies in the Great Smoky Mountains
But why do fireflies synchronize? Why should thousands of males so carefully coordinate their behavior to flash in unison, all of them marching to the beat of a single drummer? According to sexual selection theory, these males should be competing fiercely with each other for the chance to mate. So why synchronize?
“Tis strange – but true; for truth is always strange. Stranger than fiction.”
– Lord Byron, Don Juan (1823)
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
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.
Aerial pupation (photos from Faust 2012)
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.
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