40 Fun Facts About Fireflies

Fireflies are neither flies nor true bugs; the glowing insects of summer evenings actually belong to which group?

Beetles they are: fireflies make up the family Lampyridae, about 2,000 soft-bodied species whose front wings form covers called elytra.

Female Photuris fireflies copy the flash code of another species so that the males who fly in become what?

A meal is what the hopeful male becomes: the so-called femme fatale eats him and keeps his defensive toxins for herself. Her own body cannot make those chemicals.

What nickname do scientists give a firefly's glow because it produces almost no heat?

Cold light is the term: a firefly's lantern gives off almost no heat and no infrared, while an old incandescent bulb loses about 90% of its energy as heat.

Most firefly larvae are hunters that inject digestive fluid into which soft-bodied garden animals?

Snails and slugs are the main course, and the victim can be 200 times the weight of a glow-worm larva. The bite slowly paralyses it and turns it to a broth.

In Disney's The Princess and the Frog, Ray the Cajun firefly is in love with Evangeline, who is really what?

A star is the truth about Evangeline: Ray takes the Evening Star for a lady firefly. Her name nods to a 19th-century poem by Longfellow.

Crowds gather at Elkmont in the Great Smoky Mountains each year to watch fireflies flash in unison in which state?

Tennessee hosts the show: Photinus carolinus was the first North American firefly found to flash in sync. Males fire a burst of flashes, then all go dark together for eight seconds or more.

Which US state became the first to adopt a firefly as its official insect, after a campaign by elementary school pupils?

Pennsylvania chose the firefly in 1974 after pupils at Highland Park Elementary learned that one species carried the state's name. They wrote letters, ran petitions and handed out bumper stickers.

Grave of the Fireflies, the animated war film about two orphaned siblings in Kobe, was made by which Japanese company?

Studio Ghibli animated the 1988 film, the first that director Isao Takahata made there. It adapts a semi-autobiographical short story by Akiyuki Nosaka.

Which electronica act topped the Billboard Hot 100 with Fireflies, a single Adam Young wrote during bouts of insomnia?

Owl City is Adam Young's one-man project, and the song recalls the fireflies of his Minnesota hometown, Owatonna. It also reached number one in the UK and Australia.

What do adult European glow-worms eat during the few summer weeks they spend glowing, mating and laying eggs?

Nothing passes their lips, because adult glow-worms have no mouthparts. They run on reserves built up during two or three years as hungry larvae.

Japan's graduation song Hotaru no Hikari, meaning 'Glow of a Firefly', borrows the tune of which Scottish song?

Auld Lang Syne supplies the melody, set to new Japanese words in 1881. Shops and restaurants play it at closing time to usher customers out.

Luciferin and luciferase, the chemicals behind a firefly's glow, take their names from a Latin word meaning what?

Light-bearer is the meaning of the Latin lucifer, built from lux and ferre, to carry. The two names were coined in the 1880s for the ingredients of living glow.

The common eastern firefly is nicknamed the big dipper because flashing males swoop in the shape of which letter?

J is the shape: the male dips, then lights up on the upswing, drawing a glowing hook in the air. The flight path and flash together catch the eye of a partner resting on the plants below.

Which picture-book author put twinkling lights in the pages of The Very Lonely Firefly?

Eric Carle liked to give his books an extra dimension: this one twinkles, and The Very Quiet Cricket chirps. His hungry caterpillar has sold tens of millions of copies.

Which Italian poet compared the flames of Hell's eighth ditch to fireflies seen by a peasant on a summer evening?

Dante Alighieri used the image in Canto XXVI of the Inferno, written in the 14th century. The Italian word he knew the insect by is lucciola.

Visitors to the Great Smoky Mountains firefly display are asked to cover flashlights with cellophane of which colour?

Red is the rule in the Smokies and at Congaree, because bright white beams can disrupt the flashed messages between fireflies. Even a filtered torch should point at the ground.

Male common eastern fireflies flash every five to seven seconds, but the gap shortens as which condition rises?

Temperature sets the tempo: the warmer the evening, the quicker the flashes come. A watching partner answers each one after a pause of a second or two.

The common eastern firefly, the most common species in North America, is typically found east of which mountains?

The Rockies mark the western edge of its range. Genetic studies suggest its ancestors started out in Texas and spread north and east from there.

Luciferin is the compound that a firefly's glow reaction consumes; what kind of molecule is luciferase, which drives it?

An enzyme is what luciferase is, acting on the luciferin. The railroad worm glows in two colours from a single luciferin because it makes two different luciferases.

The glowworms that light the ceiling of New Zealand's Waitomo caves are the larvae of which kind of insect?

A fungus gnat it is: each larva dangles sticky silk threads and glows to lure small flying insects into them. Europe's glow-worm, by contrast, is a true firefly.

Hygiene swab tests use firefly luciferase because it glows on contact with which molecule that powers living cells?

ATP makes the firefly chemistry shine, and the glow rises in step with the amount on the swab. Since the molecule is found in and around living cells, a bright result signals microbes.

In the common European glow-worm, which adults do nearly all the glowing, climbing plant stalks at night to shine?

Wingless females are the glowers: they look like larvae and can be twice the size of the flying males. A male can spot the lamp from up to 45 metres away.

Fireflies taste foul to birds because they carry lucibufagins, steroids resembling the poison of which animals?

Toads of some poisonous species make similar heart-acting steroids, called bufadienolides. The chemicals make fireflies unpalatable to spiders as well.

Based on genomic analysis, the last common ancestor of all living fireflies is thought to have glowed which colour?

Green is the inferred ancestral glow. The oldest fossils, sealed in amber about 99 million years ago, already have clear lanterns.

The winter firefly Ellychnia corrusca flies by day and has no lantern as an adult; what does it signal with instead?

Pheromones do the job: scent was the original way fireflies called to each other, before flashing evolved. The larvae still carry two glowing lanterns.

Female Photinus fireflies judge suitors partly on a protein-rich sperm package that biologists call a nuptial what?

Gift is the word: the package feeds the eggs she will lay. Suitors that have not mated before offer bigger ones and are chosen more often.

Every firefly larva glows, so biologists think the insects' light first evolved for which purpose?

Warning predators came first: the glow advertises that a larva tastes bad. Only later was the light co-opted by adults as a courtship signal.

In a Chinese tale from the Book of Jin, the student Che Yin relied on fireflies in order to do what?

Study after dark was the aim, since he had no other lamp. The image of the industrious student opens a Japanese song heard at graduation ceremonies.

Visitors to the Smokies' firefly display must stay on the trail because the fireflies replying to the fliers sit where?

On the forest floor is where the dimmer partners wait, so a step off the path can crush them. They flash their replies during the dark pauses in the display overhead.

Firefly Aerospace named its Moon lander after which steadily glowing firefly of the southern Appalachians?

Blue ghost males glow steadily instead of flashing, drifting a few feet above the ground. The lander of that name touched down safely on the Moon in March 2025.

When handled, the common eastern firefly oozes unpleasant, sticky fluid along its wing covers in which defence?

Reflex bleeding is triggered by touch, and the fluid is laced with defensive steroids. Ants that attack can end up tangled in the sticky mess.

The oldest known firefly fossils, about 99 million years old, lie preserved in amber from which country?

Myanmar is the source: its Burmese amber holds Protoluciola and Flammarionella, two fireflies from the age of dinosaurs whose glow organs are clearly visible.

Japan's lost greatsword Hotarumaru, or 'Firefly', is named for a legend that fireflies did what to the blade?

Repaired its flaws overnight, the legend says. The original sword has been missing since the end of World War II, and fans crowdfunded a replica for the Aso Shrine.

Japan's genji-botaru firefly, possibly named after a samurai clan, raises its larvae in which unusual habitat?

Stream beds are home: the gilled larvae cannot swim, so they crawl along the bottom of small ditches and brooks. Adults emerge around June and live for under three weeks.

Which state's official insect is Say's firefly, named for naturalist Thomas Say, who worked at New Harmony?

Indiana adopted Say's firefly, Pyractomena angulata, whose flash is amber-orange. Say has been called the father of American descriptive entomology.

Boat tours at Kampung Kuantan carry visitors past riverside trees full of fireflies flashing in unison in which country?

Malaysia is home to the Kampung Kuantan Firefly Park, in Selangor, which drew over 57,000 visitors in 2018. The fireflies depend on mangroves, so the tours are an argument for protecting them.

Which poet wrote Fireflies in the Garden, which a son passes off as his own in the 2008 film of that name?

Robert Frost wrote the short poem. The film features Julia Roberts, Ryan Reynolds and Willem Dafoe as members of a feuding family.

Which South Carolina city's minor league baseball team is named the Fireflies after displays at nearby Congaree?

Columbia picked the name from more than 2,300 entries in a public contest. Congaree National Park is one of the few places in North America where fireflies flash in unison.

Fireflies undergo complete metamorphosis; what is the resting stage between larva and adult called?

Pupa is the term for the stage, which lasts one to two and a half weeks in fireflies. It is far shorter than the larval stage, which can run to two years or more.

Which weather often halts a night's synchronous firefly display in the Smokies, even though mist usually does not?

Heavy rain often stops the flashing for the evening. The park predicts each year's peak nights from the warmth of the soil rather than the calendar.