Fireflies in the Garden
Here come real stars to fill the upper skies,
And here on earth come emulating flies,
That though they never equal stars in size,
(And they were never really stars at heart)
Achieve at times a very star-like start.
Only, of course, they can’t sustain the part.
by Robert Frost
I just had a lightning bug settle on my deck’s screen door and send a little signal to me. But I read this past week that fireflies – lightning bugs to many of us – are a threatened species these days.
You might have some in your backyard but they are generally found in wetland habitats. The threats to them are the development of wetlands and insecticide spraying that is meant to target mosquitoes. It is the disruptions in their habitat while they are young – such as construction – that can extinguish an entire population.
This is a topic that is more likely to show up on another blog of mine – Endangered New Jersey – but I’m sure many of my readers here have childhood memories of fireflies and perhaps still are lucky enough to see them at night. I’m seeing fewer of them here in Paradelle. There are at least 125 species of fireflies in the United States, but none are protected by the Endangered Species Act.
Fireflies or lightning bugs aren’t flies or bugs. They are soft-winged beetles. What everyone knows them for is that they can produce light and this ability in a living organism is called bioluminescence and it is relatively rare.
Birds and other predators quickly learn to avoid them because many species of fireflies protect themselves from predators with chemicals called lucibufagins which are toxic in the right doses, but also extremely distasteful.
The light comes from special organs in their abdomens that combine the luciferin with oxygen. Entomologists think they control their flashing by regulating how much oxygen goes to their light-producing organs.
Fireflies use that blinking to find mates but it may have evolved as a way to ward off predators. The males fly around and flash a signal unique to their kind, and the females watch for males. When a female sees one doing a good job of making her species’ signal, she flashes back with a species-appropriate flash of her own. And maybe they will mate.
Scientists think the males synchronize so everyone has a chance to look for females. These displays can be quite large and spectacular and in some places (like one forest in Tennessee) crowds assemble to watch. (see video)
To most of us, fireflies are kind of magical and harmless creatures. They don’t bite. They don’t do significant damage to plants. They just want a stable woodland, meadow or marsh habitat. Their lifecycle runs a year or more and they spend most of their lives as larvae preying on earthworms and other animals in the soil or leaf litter. Oddly, most adults don’t feed at all.