Spiritus mundi and synchronicity

The fascinating world of fireflies

When my siblings and I were young we caught all kinds of wildlife. I loved to feel garter snakes slithering through my hands or to watch a (no doubt utterly freaked out) frog make a dash from my open hands to safety. I liked to think I was saving the animals from some dried out or hungry fate as I provided them with leaves or whatever I thought they’d like. Though come to think of it, I can’t recall ever seeing any of my captives eat or drink. My favorite of these dodgy activities was capturing fire flies and putting them in a jar, carefully prepared with holes poked into the lid. As an avowed bleeding heart, I now cringe at the thought of some of those activities. Though I still connect to those moments of nature appreciation, I now do it in a rather more cereberal way. Recently, I was enjoying a firefly show in my back garden which ranged all from the ground up to the top of the tulip trees. As my gaze swept further upward toward the flickering stars, I wondered if there is a link between my fascination with fireflies and with starlight. Points of light in the dark sacred night, what a wonderful world.

Until researching this article, I thought that fireflies only existed on the east coast of the US. That’s completely wrong. There are over 2000 decribed species of fireflies across the globe. Despite their various names such as lightening bugs and glow worms, they are not flies nor worms nor even true bugs but rather are beetles. Different fireflies glow yellow, green, orange or blue. The US alone has over 200 speices, while the UK has just one Lampyris noctiluca. Amongst Lampyris noctiluca only the female glows and she never flies. In fact, she never takes on an adult form. Instead she stays in larval like state, or larviforme, during her reproductive phase. Though she can glow in all the stages of her life, she is brightest when in her larviforme and trying to attract mates.

Lampyris noctiluca, like all fireflies, has 4 life stages: egg, larva, pupa and adult. All beetles have these four lifestages. The knowledge of these life stages led me to wonder how closely related beetles are to butterflies? Scientists used to think the two groups were quite distantly related but genetic analysis showed that butterflies (and fruit flies and mosquitoes which also have these 4 life stages) are more closely related to beetles than they are to bees and wasps. As a little aside, genetic analyses of this group of insects also made scientist discard the notion that social behavior in insects evolved repeatedly in favor of the theory that social behavior only evolved once in a common ancestor of egg-larva-pupa-adult species. Beetles are thought to have subsequently lost their social behavior.

The typical firefly lifecycle goes something like this. Eggs are laid in midsummer near the ground or just below the soil’s surface. 3-4 weeks later lightning bug larva emerge from the eggs. The larva stage of all fireflies glows to one extent or another. These larvae rather gruesomely inject digestive juices into their prey which immobilizes and liquefies the slugs, snails and worms they like to eat. The larvae overwinters, sometimes even living in this stage for 2 full winters. When spring comes, the larvae build a small mud chamber or sometimes attach themselves to tree bark and then hang themselves upside down. They shed their exoskeletons, several times, and enter their pupal stage. Transformative cells activate within the pupa, which basically turns to mush before the matter inside reorganizes into an adult firefly beetle. This pupa stage lasts about 10 days. Then the adult emerges and this is when we witness firefly magic.

Each species of bioluminescent fireflies has its own pattern of flashing. For instance, the fireflies of the Smokey Mountains of Tennessee include Photinus brimleyi which flashes at intervals of 10 seconds or longer, and Photinus macdermotti which has a double flash of yellow with 4-5 seconds between pairs of blinks. Also in the Smokies are Photinus pyralid, which display a sustained yellow light as the male flies upward sweeping out a letter J like pattern. But most famous in the Smokies is Photinus carolinus which flashes 5-8 times, followed by a rest of 8-10 seconds, then repeats. But that’s not all - big groups of Photinus carolinus light up and go dark at the same time. They flash in synchronicity. I should dearly love to see this display, indeed it is a very popular tourist destination. There are synchronous fireflies in Southeast Asia as well - apparently even more spectacular than the Smokey mountain fireflies.

The big question is how and why these lightening bugs synchronize their flashing. We know that adult fireflies flash to find mates. And larval fireflies flash to signal that they are unpalatable. Adult fire flies are pretty much single track sex maniacs, some don’t even eat when they are in this stage. And it’s no good to flash and attract the wrong species, which explains the different flash patterns. But scientists don’t how or the why they synchronize their flashes, though they’ve long suspected that it is probably about mate finding as well. A study published in 2016 found that when female Photinus carolinus were shown a set of synchronous flashes, they responded 80% of the time. Whereas when they were shown flashes out of sync they only responded 10% of the time. The researchers suggested that because the males are often flying when they flash, the females would find it difficult to decipher the flashes as they moved across the sky. But if all of her species were signaling at the same time, the females could process the information more easily. Whether or not she is unable to process the spatial information of a lone flasher or she chooses not to process a single potential mate flashing is a question the scientists hope to unpick next. I shall hold my tongue as to any corollaries or biases in the scientists’ interpretations about females, spatial relations and reacting to male posturing.

While research into firefly luminescence is worthwhile simply for the fascination factor, it turns out that firefly luminescence research has improved flash light and flare technology and has many medical applications. Doctors use firefly luminescence to image tumors in patients, as well as to visualize gene expression and regulation. It’s also been used to study the link between the placenta and fetus, to study HIV transmission and to monitor blood flow.

Finally, how does firefly fire arise? Fireflies have a special lighting up organ which illuminates when oxygen combines with calcium and a couple other chemicals. It turns out the lightening bugs can regulate the flow of oxygen into the organ, and thus regulate their flashing. It seems that their flashing must be a voluntary response given that the big groups of the lightening bugs that synchronize their flashing do so based on being able to see others flashing. That’s pretty wild.

Unfortunately, like other wild creatures, the numbers of fireflies are decreasing. We are encouraged to not use pesticides, for this kills the larval stage of fireflies, to leave leaf litter around to provide habitat for the larval stage, and to avoid outdoor lighting as much as possible as this interferes with the mating. If you think its a bit mad to live in the dark to protect fireflies, perhaps the lyrics of The Police’s song “Synchronicity” will help: “A star fall, a phone call. It joins all, synchronicity”. When we act to protect nature, we are also acting in our own best interest. And beyond self-interest, there is perhaps another dimension to the blink of fireflies - as the song “Synchronicity” also says “We can dream spiritus mundi”. Perhaps firefly blinking is part of the world’s spirit, catching our attention with magic and synchronicity, sending us a message.