Right up front, it’s confession time: I’ve never seen a firefly in my life. I haven’t spent much time outside of the Pacific Northwest, and fireflies just aren’t abundant here. But even without the firsthand experience of witnessing their display, I’m fascinated by their ecological and cultural significance. The Germans have a word (because of course they do) for feeling nostalgic for a place you’ve never been: fernweh, and it literally translates to farsickness. It’s the only way I can describe how I feel about the south and this phenomenon I’ve never seen.
Fireflies are not flies, but rather beetles belonging to the family Lampyridae. They are commonly found in temperate to tropical climates, in humid and marshy habitats where their larvae feed on slugs and snails. Escargot, anyone?
All larvae belonging to the Lampyridae family exhibit bioluminescence, the method by which fireflies get their distinctive glow (Although I’ve never seen a firefly, I’ve experienced other bioluminescent organisms: bioluminescent algae in the Puget Sound). Bioluminescence is a chemical reaction: The enzyme luciferase acts on the light emitting compound found in the beetle’s abdomen (the luciferin), and will produce light in the presence of magnesium ions, ATP, and oxygen. Firefly larvae use bioluminescence as a method of deterring predators, while the adults (at least the adults that produce light) use it as a method of attracting a mate.
Sadly, like many insect families, fireflies are on the decline, not only because of habitat loss and pesticide use, but because of light pollution. Fireflies rely on their flashy courtship ritual to attract a mate and breed; but if their desired mate can’t see the performance, they never get the opportunity. Thankfully, efforts are underway to help conserve this valuable and attractive beetle family. I recommend checking out the Xerces society Firefly Conservation page if you’re interested in learning more.