Fireflies light up the night sky – and the imagination
Mid- to late June is nightfall-sitting time for me, so I can enjoy one of nature’s coolest summer spectacles, the evening emergence of fireflies.
The annual coming of these winking, blinking flying beetles are a wonder, not to be missed. I actually begin my seasonal nightly watch in early June. This year the first firefly, or lightning bug, that caught my eye was on June 7 at 9:36 p.m. I watched for another 30 minutes, just because sitting in the afterglow and growing darkness is so pleasant, and I saw maybe two or three more blinkers. But it was a start.
From thereon the nightly numbers built slowly, a few more each night, always just after 9:30 but always by 9:45 for the first lights. By June 15 I was treated to an almost steady light-show each night, and I knew what was coming – a grand peak display of cool green blinking in my darkened Froggy Bottom. Last summer, June 30, the showing was spectacular, with hundreds if not thousands of them in action, their lights showing starkly against the woodsy creekbottom backdrop.
I am fortunate to live in the country overlooking an unbuildable, unfarmable creek bottom, for that is some of the choicest remaining land for lightning bugs. Their numbers are in decline because of loss of habitat. They do not do well on asphalt or concrete, pardon the sarcasm. And widespread, indiscriminate use of pesticides – everywhere from farmland and golf courses to suburban landscapes – has decimated lightning bug numbers. A third nemesis is more subtle yet just as powerful – increasing light pollution. Too much artificial light has so brightened our night skies in many places that it has interfered with lightning bugs’ responses to their flashes.
For it is the flashing that allow lightning bugs to attract mates, for males to find females and mate. The flashing also warns off predators. That cool green light is caused by a chemical reaction in their lower abdomens. When attacked by a predator, fireflies release tiny drops of blood containing distasteful, toxic chemicals. Studies have shown that predators like birds, toads, and even some spiders quickly learn to steer clear of fireflies. In fact, it is thought that firefly bioluminescence first evolved to ward off potential predators.
Lightning bugs as emergent adults only live a couple weeks or so. After mating and laying eggs they die. In contrast they spend up to a couple years as voracious larvae in the soil, feeding like lions on other insects, snails, and earthworms. Sometimes as larvae they are called glow-worms, which sometimes can be seen burrowed deep in the roots of grass.
It would be a shame to see these night-lighters disappear. These are creatures which have a lineage that goes back 100 million years. About 2,200 species exist worldwide, some as large as a hand. About 165 species are known in the United States and Canada. Individuals are about a half inch to an inch long, depending on species.
One night last year I was so impressed with the peak display I penned a little story about lightning bugs for my grandchildren – or for “kids” of any age. It was about how, in the early days of Earth, stardust fell on the world and through a magical transformation, fireflies – Star Twinklers – emerged. The fanciful story told that the nightly blinking by the Twinklers were signal-messages back to the Stars from these planetbound beetles. Good for the young imagination, I thought.
So, take some time tonight to stop and enjoy this quiet natural spectacle. I will be out there watching with you.