I remember childhood summer nights when the sky was full of flashing fireflies. We called them lightning bugs and glow-worms. We even sang a little chorus about them. They're plentiful in the woods behind my house. But now bees are in rapid decline, butterfly numbers are dwindling, and fireflies are facing similar problems. For years, scientists have been warning that the world’s approximately 2,000 species of fireflies are rapidly diminishing.
As more man-made environments encroach into firefly habitats, those habitats are becoming increasingly scarce. Fireflies live and breed in woods, forests, streams, lakes, gardens and wild meadows. Pesticides and light pollution are hampering firefly mating behavior as well.
Fireflies (beetles of the order Coleoptera) indicate the health of the environment. They're declining across the world due to habitat loss, water pollution, increasing use of pesticides, and light pollution. This is part of a worldwide trend toward biodiversity loss.
In many cultures, fireflies are iconic symbols. For a lot of us, they were our initiation into the wonders of Mother Nature. If we lose the fireflies, we lose a major connection to the natural world.
What can we do to help them? For starters, we can turn our own yards into small firefly nature preserves by avoiding the use of chemicals, leaving worms, snails, and slugs for firefly larvae to feed on, turning off outside lights, and providing good ground cover, grasses and shrubs for them to inhabit.
Fireflies use their flashing lights to signal each other, attract mates, and warn of danger. Scientists think human light pollution disrupts their flashes making it harder to find mates and breed. Turn off exterior and garden lights at night, close curtains and blinds, and keep your yard as dark as possible.
Most species of fireflies thrive near standing water and marshes. Ponds, streams and rivers provide good habitats for them. Even a shallow puddle of water can cause them to congregate. If possible, build a small pond or divert a small stream through your property. Fireflies are thought to eat smaller insects, grubs and snails that thrive in natural ponds and streams. Be aware that these food sources won't survive in chlorinated environments like swimming pools.
Some species of firefly larvae grow up in rotten logs and plant litter that accumulates underneath a forest canopy. Plant trees on your property. If you already have trees in your yard, leave some natural litter around them to give firefly larvae a protected place to grow.
Chemical pesticides and weed killers have a negative effect on firefly populations. Fireflies and their larvae can also come into contact with other insects that have been poisoned, or they may ingest poisons from sprayed plants. Use only organic pesticides on your lawn and garden.
Many communities spray for mosquitoes at night when fireflies are actively flashing and mating. This can eradicate firefly populations. Urge communities to implement programs to reduce standing water to prevent the growth and development of mosquitoes. By encouraging broad-spectrum mosquito control and discouraging spraying when fireflies are active, communities can both save money and affect better mosquito control. This causes fewer problems for fireflies and other creatures. Chemical fertilizers may be harmful to firefly populations as well. Using natural fertilizers will make your yard a healthier environment for them.
Fireflies usually stay on the ground during the day. Frequent mowing can destroy them. Incorporate some areas of tall grasses into your landscaping. Fireflies prefer living in tall grasses and this may boost their numbers in your yard.
Fast-growing pines and native trees are good habitat for many firefly species. They provide shade, and the low light areas beneath their canopies lengthens the amount of time fireflies have to seek a mate. Accumulated duff produced by pine trees provides an excellent habitat for earthworms and other firefly food.
For most of us, earthworms are a common sight. We don't think about their impact on fireflies. According to Smithsonian.com, "Thousands of years ago, glaciers that covered North America and reached as far south as present-day Illinois, Indiana and Ohio wiped out native earthworms". Species from Europe and Asia were likely unintentionally introduced in ship ballast or in the roots of imported plants and have spread throughout North America. The impact of earthworms is not limited to plants. The reduction of plant diversity and leaf litter affects habitat and food availability for insects such as fireflies. This negatively impacts the food chain and reduces food available to reptiles, fish, amphibians, birds, and small mammals. These non-native earthworms are having very negative effects on native earthworm species. In their larval stage, fireflies are carnivorous. They eat soft-bodied insects that live on or in the ground such as snails, slugs, worms, or other larvae. Some fireflies feed on flower nectar or pollen. Others eat smaller fireflies. Some eat nothing during their short lives.
One variety of firefly has even become famous. The Synchronous Firefly (Photinus carolinus) can be found here in Tennessee as well as these other locations. Don't miss the video at the bottom of the link.
Saving fireflies is a serious concern. Their habitats are home to many species of mammals, birds, reptiles, amphibians, flora and fauna. The more of nature we lose, the more of its protections we lose as well.
(Photos top to bottom: by Ivan Kuzmin[email protected]; By LiCheng Shih (_ESH0075) [CC BY 2.0 (https://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons; By Bruce Marlin [CC BY-SA 2.5 (https://creativecommons.org/licenses/by-sa/2.5)], By Mike Lewinski from Tres Piedras, NM, United States (Lupines and Fireflies No. 4) [CC BY 2.0 (https://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons; By Jud McCranie [CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0) or GFDL (http://www.gnu.org/copyleft/fdl.html)], from Wikimedia Commons; boy with jar by [email protected])