Secret codes and nocturnal encounters

Many a night I saw the Pleiads rising thro' the mellow shade,

Glitter like a swarm of fireflies tangled in a silver braid.

Alfred Tennyson

IT’S A SULTRY summer night. The stars are twinkling, a light breeze teases the trees, a barred owl hoots in the distance.

Perfect for a little romance.

Actually, judging from the number of little lights flitting about the woods and lake shoreline where I’m observing the night sky, there’s lots of hooking up going on.

Yes, the fireflies have come out to play on this late June evening. Their mesmerizing now-you-see-them-now-you-don’t performance is keeping me entertained while my camera soaks up photons from the great beyond. The planets Mars and Saturn are passing by the constellation Scorpius low in the south so I’m shooting some long exposures to capture this celestial grouping for posterity.

Fireflies have been synonymous with summer for me since childhood. I was fascinated by these “lightning bugs” that seemed to be visitors from a magical fairy world.

Alas, the reality is less romantic. Fireflies aren’t actually even flies, they’re soft-bodied beetles. If you held one in your hand during the day, you’d see a bug with a dark backside and an orangish front.

And those ethereal lights are actually the result of a protein reacting with an enzyme. Nothing very magical there. 

After my night among the celestial and insectoid lights, I called up Andrew Hebda, the curator of zoology at the Nova Scotia Museum of Natural History, for the scoop on these summer visitors.

There’s indeed a romantic aspect to the reason these insects light up the night. Well, romantic in a glowing beetle butt kind of way.

The light produced on the insect’s tail end is created by a fairly simple chemical reaction, Hebda explained.

“They have a photo-luminescent protein called luciferin. When it’s exposed to an enzyme called luciferase, which is released upon a given stimulus, it essentially causes the excitation of luciferin to a higher stage, and as it decays, then it releases light. It’s a very straightforward chemical decay process.”

Not so straightforward is exactly how the message “OK, turn my backdoor light on” is triggered in the beetle’s brain.  “That’s the process they don’t understand clearly,” Hebda said.

But the goal of this photochemical wizardry is clear:  Find a mate and fast. The males produce their signal in a particular pattern to tell females that they’re around, they’re available to mate, Hebda said.

Fireflies love a warm and calm summer evening. This is a stack of 29 30-second exposures taken on a country road in nova scotia. - John Mcphee

“Essentially the pattern is sort of like a Morse code, it’s very species-specific. You can use the analogy that one may be flashing an S and one may be flashing the letter P.  Based on the pattern of flashes, the potential mate will recognize that and respond to that.”

Fireflies don’t have the best eyesight so the successful light signal must be close by, he said. 

The females also use light patterns to respond to males or to attract them — both for sex or for a free lunch, it turns out. Some female fireflies mimic the light patterns of other species, lure the unsuspecting Romeo into their lair and gobble him up. Nice.

If there’s a happier ending to the love story, the female usually lays her eggs soon afterward. The mating and subsequent egg-laying usually takes place in sheltered wetlands and bays.

“You’re not going to find them in the middle of open, windy dry areas,” Hebda said. “They’re not aerodynamically designed to cope with strong winds so you tend to find them in wetland areas where you have some protection from wind ... They have to be near the appropriate habitat for both the eggs to be able to ripen and hatch and larvae to feed.”

There are about 2,000 species of fireflies across the world. The nine types found in Nova Scotia are true fireflies — some species that fall into the Lampyridae family don’t light up. Exactly how many fireflies flit around on a typical Nova Scotia summer night isn't known, Hebda said. 

“I have a farm on Cobequid Bay and there are a couple of wetland areas there and it’s not unusual to see 40 or 50 (fireflies). Within that individual one hectare of wetland, we may have several hundred individuals because, of course, you’re only seeing the males. The females will either be up in the shrubbery or down in the ground. You tend not to see those ones.”

As a zoologist, Hebda is obviously interested in the creepy crawly set. “Anything that runs, flies, swims or crawls. If it’s dead, it stinks. If it doesn’t stink, we call it palentology.” (We’ve only met on the phone but it’s clear this scientist comes equipped with a tinder-dry sense of humour). 

It’s fair to say most people don’t share his love of the insect world. Even those who enjoy the spectacle of fireflies at night would get out the broom if they spotted one of those beetles crawling across the floor in the daytime. 

“I blame our parents completely for that,” said Hebda, perhaps only half-jokingly. “Of course, we’re supposed to keep things clean ... ensuring that you don’t have vermin and insects that are crawling around.”

When it comes to fireflies, “the other elements that some people may find repulsive are masked by that absolutely gorgeous and mysterious sight. We may know the chemical processes as to how it works but still it’s a mystical thing.”

I can only agree as I later look over my exposures from the Scorpius session. A few have been firefly photobombed with short, green streaks of light. Just beetles. But pretty magical ones just the same. 

First published July 2016.
Update: Mr. Hebda retired in 2019 after 25 years as a zoology curator at the Nova Scotia Museum of Natural History