Late July is an exciting time to look at the sky in your own neighborhood. Every evening as dusk falls, thousands of tiny lights begin to blink over yards, parks, and tree lines. On our Alitaptap tracking map, volunteers have been busy logging sightings all week long.
On July 26 and 27, reports came in from all kinds of places. People saw fireflies on busy city streets like Driggs Avenue in New York City. They spotted them in suburban yards in Greenfield, Wisconsin, and Leavenworth, Kansas. Others found them in quiet parks like Lake Crabtree Park in North Carolina. Across the ocean, observers logged sightings in the countryside of England, Poland, and Belgium.
Where you live shapes what kind of fireflies you see and where they hang out. Let's look at four different habitats where fireflies are active right now, what they are doing there, and how you can watch them without causing any harm.
The Lawn and Tree Edge: Home of the Flashers
If you step out into your backyard or a neighborhood park right around sunset, you are in prime firefly territory. Most of our recent map entries come from places where open lawns meet trees, bushes, or tall grass. In places like Evanston, Illinois, and Berlin, Maryland, observers watched yellow-green lights start up just as the sun dipped low.
These night fliers are usually Common Eastern Fireflies. Scientists call them Photinus pyralis. They love the borders where mowed grass meets shade. During the hot daytime, these beetles hide down near the damp roots of grass blades or under low plant leaves. That cool, wet shade keeps them from drying out in the summer heat. If a lawn is cut extremely short, or if the dirt gets baked dry by the sun, fireflies lose their daytime shelter.
When twilight arrives, the male beetles take off first. They fly slowly, about knee-high to waist-high above the ground. As they fly, they make a special movement. They swoop downward and then pull upward, making a glowing shape like the letter J in the dark air.
They are looking for female fireflies resting in the grass below. When a female sees a male's flash, she waits a couple of seconds and flashes back from her blade of grass. It works like a secret code made of light. If you want to see this happen, stand near the shadow of a tree line where the ground gets dark first.
Shady Woods: Spotting Fireflies in the Daytime
Not all fireflies wait for the sun to go down. Over in Canada, observers in Ontario, Nova Scotia, and Quebec reported Black Fireflies during the middle of the day.
Black Fireflies look very different from their night-flying cousins. Their bodies are dark charcoal grey with thin red or yellow patches right behind their heads. Most surprisingly, adults do not light up at night at all! Instead, they fly around shady woods during warm afternoons.
How do they find each other without glowing lights? They use their sense of smell. Female Black Fireflies release special scent chemicals into the air called pheromones. A male beetle uses his wide, feathered antennae to catch those scent signals floating on the breeze.
If you walk along a shady woodland trail on a summer afternoon, look closely at tree trunks and large leaves. You might spot a Black Firefly crawling on the bark. They live near fallen logs and thick leaf piles where the soil stays damp. Damp earth is essential because it protects their eggs and gives young fireflies a place to hunt.
Grassy Banks: Glowing Females Across the Pond
On the exact same nights, Alitaptap members in High Wycombe in the United Kingdom, Greater Poland, and Bertrix, Belgium, logged sightings of European Glow-worms. Even though people call them worms, they are actually beetles and true members of the firefly family.
European Glow-worms behave in a totally different way from North American fireflies. Male glow-worms look like normal dark beetles with wings, and they fly around looking for females. But female glow-worms do not have wings at all. They look a bit like flat caterpillars.
Late in the evening, a female glow-worm crawls up a stem of grass or a mossy rock on a roadside bank. She lifts her tail toward the night sky and turns on a steady, bright green light. She does not flash on and off. Instead, she glows continuously for hours until a flying male spots her from above.
If you live in Europe or visit grassy countryside hills, keep your eyes low to the ground. Look for tiny green lights that sit completely still in the dark grass.
High in the Canopy: The Tree-Dwellers
Some fireflies prefer to stay high above our heads. In Bucyrus Township, Ohio, an observer reported Say's Firefly on July 26.
Say's Fireflies are known for appearing early in the summer, but some stay active through late July. Unlike the Common Eastern Firefly that hovers near lawn grass, Say's Firefly likes the branches of mature trees. They often sit high up in oak, pine, or fruit trees and produce quick, amber-yellow flashes.
Because they stay so high up, they can be easy to miss if you are only looking at the ground. To spot them, find a spot with old, tall trees just as the sky turns dark blue. Look up into the leaves before the sky goes completely black. You might see quick flashes flickering high in the treetops like tiny stars.
Inside the Flash: How Fireflies Make Cold Light
Have you ever touched an old light bulb after it has been turned on for a while? It gets very hot to the touch. That happens because standard light bulbs lose most of their energy as heat instead of light. If a firefly got that hot, it could not survive.
Fireflies make light through a chemical process called bioluminescence. That is a long word, but it simply means light produced by a living creature. Inside a firefly's lower belly, two special chemicals mix together along with oxygen from the air. When those chemicals combine, they create light without creating any heat at all. Scientists call this cold light because almost all of the energy turns directly into glow.
Right now in late July, adult fireflies are using this cold light to find mates and start the next generation. Soon, females will lay their eggs in damp soil under fallen leaves or mulch. A few weeks later, those eggs hatch into larvae. A larva is the young, wingless form of an insect, like a caterpillar before it turns into a butterfly. Firefly larvae live in the dirt all autumn and winter, eating tiny snails, worms, and slugs.
Four Simple Rules for Safe Firefly Watching
Firefly numbers are dropping in many places because of city lights, lawn chemicals, and lost habitat. You can help protect the fireflies in your neighborhood while watching them up close. Here are four easy rules to follow:
- Turn off your outdoor lights. Bright porch lights and floodlights make it hard for fireflies to see each other's flashes. Turn off outside lights and close your window blinds at dusk so fireflies can find their mates.
- Use a red light flashlight. White light from a smartphone or regular flashlight can startle fireflies and disrupt their flashing for several minutes. Cover your flashlight lens with red plastic tape or red paper. Red light does not disturb firefly eyes.
- Skip the bug spray on your hands. Chemical insect sprays can harm fireflies on contact. If you need bug spray, apply it to your clothes before going outside, and wash your hands before touching any plants or bugs.
- Treat caught fireflies gently. If you catch a firefly in a clean jar to observe it, place a damp piece of paper towel in the bottom to keep the air moist. Do not punch holes in a metal lid, because sharp foil edges can cut tiny bug legs. Instead, cover the top with a piece of cloth or leave the lid slightly loose. Always release your firefly back into the grass after ten minutes.
Add Your Sightings to the Map
The next time you step outside at dusk, pay close attention to your surroundings. Are you standing near a mowed lawn, a damp forest, or under high tree branches?
Notice the color of the flashes, how high the insects are flying, and the exact time you see them. Then jump onto Alitaptap and add your sighting to our map. Every single entry helps scientists protect firefly habitats for years to come.