You may have spent summer evenings chasing fireflies around the vegetable garden with a mason jar as a kid, but if it seems like there aren’t as many of those twinkling bugs lighting up the night sky these days, you’re not imagining it. Fireflies—or lightning bugs, as you might call them—are under threat, which researchers suspect has to do with habitat loss, light pollution, and widespread pesticide use, according to Firefly Watch, a citizen science project led by the Museum of Science in Boston. That’s not just unfortunate for fireflies—it’s also a bad sign for the rest of us. Looking at the health of the firefly population is a window into the health of the environment as a whole since fireflies’ population density is directly correlated to the availability of healthy habitat, notes Clemson University’s Vanishing Firefly Project.
So what can you do about it? Here are six steps experts recommend taking in order to turn your yard into a firefly’s paradise.
High grasses and shrubbery are a key part of a firefly’s ideal habitat. The National Gardening Association recommends letting the perimeter of your yard grow wild to create these favorable conditions. At the very least, mow less frequently to decrease the risk of killing fireflies as they rest on tall blades of grass during the daytime. If you're concerned about leaving brush and tall grass because ticks tend to hang out there, you could compromise and only let the brush build up on the outer edges of your property.
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Like mosquitoes, fireflies love moisture, standing water, and marshy areas, according to firefly researcher Ben Pfeiffer. Most live and mate where forests and fields meet streams, but they also congregate around small puddles and other standing water during the mating season. If you're not concerned about mosquitoes where you live, consider including a small pond in your backyard landscape will provide them with habitat.
Fireflies glow for two reasons: to warn predators to stay away (their blood is toxic) and, more importantly, to attract a mate. According to The Vanishing Firefly Project, there can be as many as five species of fireflies active in one area at a time. Males use distinct light patterns to let females of the same species know where they are. The females, who typically remain perched on tall grasses, signal back if they’re interested in a nearby suitor. Bright outdoor lights can outshine fireflies’ tiny lanterns, interfering with mating behavior, so lend fireflies a hand and by flipping off the switch at night.
One of the biggest threats to fireflies is habitat loss. As we turn forests, meadows, ferns, and fields into construction sites, we destroy the damp, wooded areas where fireflies lay their eggs. Terry Lynch, a naturalist and firefly expert, writes that planting native trees—especially pine trees—helps fireflies in a couple of ways ways: Pines’ thick canopies block out beams of artificial light that could interfere with mating, and needles and branches that drop to the ground create the ideal spot for larvae to florish beneath the tree.
You probably know insecticides don’t just target pests—they kill the good guys, too. The Vanishing Firefly Project cites the widespread use of chemical pesticides as one of the leading causes of firefly decline. In addition to being hit with sprays directly, fireflies are also poisoned by pesticide residue that remains on grass and leaves.
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Some species of fireflies lay their eggs in rotten logs and other brush on the forest floor, and the larvae feast on the slugs, snails, and worms that this type of damp habitat attracts. Try creating more habitat for firefly larvae by letting some brush and logs accumuate under the trees in your yard.