It is late July. If you walk outside right as the sun dips below the horizon, the night sky comes alive with small floating sparks. But what you see depends on where you live.
Over the last two days, observers on Alitaptap logged firefly sightings from backyards in Pennsylvania all the way to grassy fields in England and tropical forests in Bolivia. July is a major shift on the firefly calendar. Some species are finishing their summer flight. Others are reaching their peak. Some fireflies do not even flash at all.
Here is what is happening in the firefly world right now, and what you can spot in your own neighborhood tonight.
Eastern North America: Flashers in the Fields
In the eastern half of North America, late July brings peak evening activity. The Common Eastern Firefly is the most widespread species on the map right now. Over the past 48 hours, Alitaptap users reported them in Pittsburgh and Cleveland, down through Maryland and Tennessee, and all the way south to Saratoga, Texas.
These fireflies love open lawns, parks, and meadow edges. Male fireflies fly low over the grass, usually two to three feet high. When they flash, they swoop down and then rise up in the air. This arc makes a bright yellow light shape like the letter J. If you watch a dark field for five minutes, you will see dozens of these glowing hooks in the dark.
Common Eastern Fireflies start flashing right at dusk. They stay active for about an hour. Once full darkness sets in, many rest on plant leaves for the night.
They are not alone in the eastern sky. In places like Ottawa, Ontario, and Ithaca, New York, observers logged the Little Gray Firefly. This beetle is smaller and lighter in color than the Common Eastern Firefly. It prefers shaded forest edges and low bushes over wide lawns. Its flash is quicker and softer.
You might also see fireflies during the day, even though their lanterns stay dark. In Val-d'Or, Quebec, and across Ohio, Alitaptap members found the Black Firefly. These insects fly in full daylight. They do not use light to talk to each other. Instead, they release special scents into the air to find mates. If you see a flat, dark beetle with orange or red marks near its head crawling on a tree trunk at noon, you are looking at a day-active firefly.
Western North America: Secret Lights in the West
Many people believe fireflies do not live in the western United States. That idea is wrong. Western fireflies are out right now, but they behave differently than eastern species.
In late July, observers in Paradise and Layton, Utah, as well as Broomfield, Colorado, reported the Dark Firefly. Dark Fireflies live near mountain streams, marshes, and damp canyons. Male Dark Fireflies do not usually fly around making flash patterns over tall grass. In many western species, males do not light up while flying.
To find them, you must look down at the ground. Female Dark Fireflies sit in damp moss or low grass and glow softly. Their light is a steady, quiet beam rather than a blinking flash.
Further west, in North Plains, Oregon, an observer spotted a California Glowworm on July 27. Adult female California Glowworms do not look like beetles. They look like pale, segmented grubs or caterpillars. They have no wings, so they cannot fly. At night, they lift their bellies in wet soil and emit a bright green glow. They use this light signal to attract flying males from the dark sky above.
If you live in the western states, skip the dry open lawns. Walk along river paths, wet mountain meadows, or shady forest trails right after sunset. Bring a red light and scan the damp earth.
Europe: Wingless Females and Nighttime Beaches
Across the Atlantic Ocean, Europe is having its own late-July glow season. European fireflies act very differently from American ones.
In the United Kingdom, observers logged European Glow-worms at Trewent Beach in Wales and in Cornwall, England. Sightings also came in from Vizcaya in northern Spain and Slatina in Serbia.
The European Glow-worm is famous because males and females look totally different. The male looks like a normal brown beetle. He can fly, but he has no light organ on his belly. He flies through the dark night searching for light.
The female glow-worm cannot fly. She has no wings at all. She looks like a dark grey beetle larva. Every night in July, she climbs up a tall blade of grass, a stone wall, or a wooden fence post. Once she reaches a good spot, she turns on her light organ.
Her light is bright, steady, and yellowish-green. She stays still for hours, glowing like a tiny streetlamp. When a flying male sees her light from above, he drops down to land beside her.
European Glow-worms love chalky hillsides, riverbanks, and paths near beaches. Because females cannot fly, they cannot move far if their habitat changes. If a grassy path is paved, that local group can vanish. That is why tracking them on Alitaptap in late July is so important for scientists.
Europe also has a newcomer this month. In Saint-Jean-Pla-de-Corts in southern France, an observer logged Photinus signaticollis. This species originally comes from South America. In recent years, it has spread into parts of southern Europe. Scientists are watching map data closely to see how this new species affects native European insects.
The Equator and the Southern Hemisphere
While North America and Europe enjoy summer nights, July is winter south of the Equator. In cool southern places like Argentina or southern Australia, firefly activity is quiet right now.
However, near the Equator, the weather stays warm all year long. On July 28, an observer in Baures, Bolivia, logged a Spotted Tortoise Firefly.
Baures is located in tropical wetlands in South America. It stays warm and humid in July. Spotted Tortoise Fireflies belong to a group called Aspisoma. They get their name from broad, flat wing covers that look like a turtle shell. These tropical fireflies fly near river margins and wet forests, flashing bright green signals among the trees.
This observation reminds us of a basic rule about the firefly calendar. Fireflies do not follow human months on a wall calendar. They follow warmth, moisture, and food.
What to Look for Tonight
No matter where you live, late July is a great time to step outside and become a citizen scientist. Here is your checklist for tonight.
First, check the time. Start your search about 20 minutes after sunset. In late July, dusk arrives later in the evening, so be patient.
Second, pick a damp location. Fireflies need moisture to survive. Check near the edges of ponds, creeks, wet meadows, or under tall trees. Avoid lawns that are cut very short or sprayed with chemicals.
Third, keep the area dark. Turn off your porch lights. Bright white light from house lights, cars, or smartphones confuses fireflies and interrupts their mating signals. If you need a light to walk safely, cover a flashlight with red tape or red plastic. Fireflies cannot see red light easily, so it will not disturb them.
Fourth, observe the pattern. Is the light blinking or steady? Is it moving through the air or sitting on the ground? Is it yellow, green, or orange?
If you spot a firefly, write down the time and place. Then ask an adult to help you drop a pin on the Alitaptap map. Every single record helps scientists protect these glowing insects for years to come.