- Catching fireflies is an important part of summer.
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Like Fourth-of-July fireworks, cool swims on hot days, and lazy vacations, fireflies are a sign of summer. Many of us have cherished memories of spotting and catching them during warm summer evenings and running through fields that sparkled as if strewn with stars. But there are signs our kids may not grow up with the same firefly memories we had. That’s because fireflies are disappearing from marshes, fields and forests all over the country—and all over the world. And if it continues, fireflies may fade forever, leaving our summer nights a little darker and less magical.
Why Are Fireflies Disappearing?
Nobody knows for sure. But most researchers blame two main factors: development and light pollution.
Most species of fireflies thrive as larvae in rotting wood and forest litter at the margins of ponds and streams. And as they grow, they more or less stay where they were born. Some species are more aquatic than others, and a few are found in more arid areas—but most are found in fields, forests and marshes. Their environment of choice is warm, humid and near standing water of some kind—ponds, streams and rivers, or even shallow depressions that retain water longer than the surrounding ground.
The problem is that in America and throughout the world, our open fields and forests are being paved over, and our waterways are seeing more development and noisy boat traffic. As their habitat disappears under housing and commercial developments, firefly numbers dwindle. Logging, pollution and increased use of pesticides may also contribute to destroying firefly habitat and natural prey.
Human traffic is believed to disrupt firefly habitat as well. While scientific studies have only been done for the past few years, there’s plenty of anecdotal evidence in areas that were once full of fireflies—and much of it goes back generations. Some areas once had so many fireflies that they profited from running firefly tours in marshes and forests—but since human traffic has increased, firefly populations have gone down.
Too Much Light At Night
Scientists don’t know enough about fireflies to tell for sure. But the signs are indicating light pollution as a major factor in the disappearance of fireflies all over the world.
Both male and female fireflies use their flashing lights to communicate. Some species synchronize their flashes, sometimes across large groups of thousands of insects. All species speak a language of light—scientists believe they use it to attract mates, defend their territory, and warn off predators.
Human light pollution is believed to interrupt firefly flash patterns. Scientists have observed that synchronous fireflies get out of synch for a few minutes after a car’s headlights pass. Light from homes, cars, stores, and streetlights may all make it difficult for fireflies to signal each other during mating—meaning fewer firefly larvae are born next season.
Where fireflies once had uninterrupted forests and fields to live and mate, homes with landscaped lawns and lots of exterior lights are taking over. The reduction of habitat and the increase in lighting at night may all be contributing to make fireflies more rare.
Fireflies are fascinating creatures that light up our nights and bring a sense of magic and mystery to our environment. If they disappear, it will be a great loss to habitats and generations of people all over the world.
Essentials Field Guide to Insects
One of the biggest factors in firefly disappearance in habitat destruction. If a field where fireflies live is paved over, the fireflies disappear forever. They don't migrate.
People apply broad spectrum pesticides on their property to control insect pests, but many pesticides may also kill non-pests including fireflies and their larvae. Fireflies are not pests.
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