After lamenting to my daughter about the masses of lightning bugs that illuminated the backyard of my childhood, they have finally greeted us again in Illinois. Even with its dwindling population, the firefly's nocturnal dance can turn a cow pasture into an exotic locale.
But they are also a sad sign of the times. As a kid I found them everywhere and not a night went by when I didn't turn a grass-filled jar into a hotel for as many bugs as I could catch. Never would I have considered that one day I wouldn't allow my own child this same ritual. But like other wildlife, human encroachment has had a profound effect on the life cycle of the lightning bug.
Fireflies are actually beetles, comprising over 2,000 species that prefer the temperate climates of Asia and America. They love moisture and tend to settle around water sources such as rivers and ponds, and even backyard landscapes that don't contain chemical treatments. Adults spend their days hanging out in shrubs, trees, high grasses and, of course, the foliage surrounding their water supply. Eggs are laid underground, and growing larvae hibernate in the bark of trees or by burrowing into the soil.
While the adult bug is one of the most benign in the insect world, the larva is a predator. Larvae feast on slugs, snails, worms and even the larvae of other species. Once a beetle reaches adulthood it consumes nectar and pollen, while it is suggested that some don't eat anything. The lifespan of a mature lightning bug reaches two months, just enough time to mate and deposit eggs back into the soil.
The mysterious flashing light emitted by the beetle has earned it a seat in art and lore worldwide. Some species can actually luminesce as an egg, the wingless versions and larvae often called glow worms. The light itself comes from organs under the abdomen, where bioluminescence occurs when oxygen mixes with ATP (adenosine triphosphate), magnesium and the enzyme luciferase (produced by the bug). This light can be yellow, green, or a pale red, and is often described as a combination of these. The flashes per second are determined by species type and each is unique.
While this makes for a fantastic light show for us, the blinking serves as a communication system for the beetle. First and foremost this is the lightning bug's mating signal. The adults are attracted to the nocturnal display and are guided to each other by the light. The illumination also acts as a defense mechanism, discouraging predators by indicating that they might be poisonous, but will certainly taste terrible if consumed.
Some species are carnivorous and use the light as a calling card for potential meals. Female fireflies of the genus Photuris emit the mating signal for the genus Photinus to attract the male and unleash their inner Hannibal Lecter on them. Other acts of imitation are surprisingly common among the insects and are used to stave off the competition for mates as well as to lure in mates from another genus.
Think your backyard residents put on a great performance? Thousands of tropical fireflies in Southeast Asia synchronize their twinkles when in large groups, an occurrence known as biological synchronicity. This has been seen for many years in Malaysia and the Phillipines, and has recently been noted in Elkmont, Tenn., and the Congaree National Park in South Carolina. Scientists cannot explain this phenomenon but attribute it to diet, social interactions, and possibly altitude.
Still these amazing creatures are disappearing. Development, logging, pollution, pesticides, and human traffic all contribute to the demise of the population. One of the biggest setbacks the lightning bug faces is light pollution.
Fireflies are so sensitive to any radiance that they often stay hidden during a full moon. Even the simple act of leaving your porch light on can disrupt their mating. For an insect with such a short mating season, this has devastating effects on its population.
To help the beetles thrive in your area, here are a few tips from www.firefly.org
- Turn off exterior lights.
- Let logs and deciduous litter accumulate, giving them a home and feeding area for larvae.
- Create water features in your landscaping — and this doesn't include your chlorinated pool!
- Avoid pesticides and use natural fertilizers.
- Don't over mow, plant trees and introduce more earthworms to your yard.