Fireflies are the stuff of magic and faerie, at least in the minds of children (and more than a few grown-ups). They rule the midsummer night, dipping and dancing across backyards, parks, and meadows, keeping their lights on well into the small hours of the morning. Many a summer childhood memory involves an empty mayonnaise jar, a few holes nail-punched in its lid, and some hand-caught bits of starlight flashing inside.

About 2,000 species of fireflies exist worldwide, and nearly 150 of them live in North America. All have eggs, pupae, and larvae that glow, which is why the larvae are commonly called “glowworms.” While adult fireflies light up to find a mate, or in some cases, a meal, glowworms emit light to warn would-be predators to stay away. Glowworms are predatory, feeding on slugs, snails, and other soft-bodied prey. Depending on the species, adults may feed on nectar, or, in a few cases, male fireflies of other species. The carnivorous females do this by mimicking the mating flashes of other fireflies, which lures amorous (and clueless) males to be devoured. One species, the Blue Ghost, lives in the Smoky Mountains and synchronizes its flash so that every firefly in the field flashes at once.

Also called “lightning bugs,” fireflies are neither flies nor bugs — they’re beetles. Their light, or bioluminescence, is incredibly efficient with nearly 100 percent of its energy released as light. By contrast, 90 percent of the energy used by an incandescent light bulb is released as heat. The active enzyme of bioluminescence, luciferase, has medical and research applications, and scientists can now produce it artificially.

Where Have All the Fireflies Gone?

Unfortunately, fireflies’ spectacular light displays have been fading away, blinking out as fewer and fewer fireflies join the show each year. The reasons include loss of habitat, widespread use of pesticides, and increased light pollution. We can save the fireflies, but we need to act now.

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We destroy prime firefly habitat at an alarming rate; clearing, leveling, building on, and paving over grasslands, meadows, fields, and forests in our quest for a place of our own. While adult fireflies can move out when the bulldozers move in, glowworms, eggs, and pupae cannot. Even adults are under pressure from the excessive lights of modern life; street lights, headlights, security lights, and even porch lights and windows can drive them away.

Create a Firefly Sanctuary

What can we do about the increasing firefly shortage? To borrow a line from Field of Dreams, “If you build it, they will come.” Provide fireflies with a safe environment, and they’ll move in, lighting up your backyard within a year or two. They have simple needs: relatively tall grasses, moist soil, and darkness at night, all in a pesticide-free environment.