What a firefly looks like and why it shines: interesting facts


Representatives of each species emit light in the form of flashes of a certain frequency and brightness, which helps congeners to find each other during the breeding season. When a female sitting in the grass or on a branch sees flashes emitted by the male of her species, she sends back the same light signals to the future partner. The glow organs in fireflies are located at the end of the abdomen. Here are large cells that contain organic matter luciferin and protein-enzyme luciferase. As a result of their interaction with oxygen, a flickering greenish-yellow light appears.

Interestingly, the firefly can not just glow, but also to regulate the "lighting": change the power of the light and even make it intermittent. By the way, not only adult insects are glowing: even tiny larvae have this “gift”.


Fireflies are widespread in North America, Asia and Europe. They can be found in deciduous and tropical forests, in glades, meadows and marshes. This is a representative of a large family of the order of beetles, which has an amazing ability to emit quite bright light.

Firefly is an insect belonging to the Firefly family (Lampyridae), a beetle species. The family has over two thousand species. Especially widely represented in the subtropics and the tropics, rather limited - in the temperate zone. In the countries of the former Soviet Union, there are seven genera and almost 20 species. And in our country, many know what a firefly looks like. In Russia, 15 species are registered.

For example, nocturnal insects are Ivanovo worms that spend the day in fallen leaves and thick grass, and at dusk they go hunting. These fireflies live in the forest, where they hunt for small spiders, small insects and snails. The female cannot fly. It is completely painted in brown-brown color, only on the underside of the abdomen there are three segments white. Here they emit a bright light.

Fireflies living in the Caucasus, glow in flight. Sparks, dance in the thick darkness and give the southern night a special charm.

What does a firefly look like?

I must say that in daylight, these bugs look quite modest, even, one might say, inconspicuous. The body is narrow and elongated, the head is small with short antennae. Yes, and the size of the firefly can not boast - on average from one to two centimeters. The body in different species is colored dark gray, black or brown. Many species have pronounced sex differences: males are larger than females. In addition, males look very similar to cockroaches. They can fly, but they do not shine.

What does a female firefly look like? It looks like a worm or a larva. She has no wings, so she is inactive. But it is the female that glows in most species, attracting males to her. These beetles do not have lungs, and oxygen is transmitted through special tubes - tracheoles. The supply of oxygen is “stored” in the mitochondria.


Fireflies do not belong to collective insects, but despite this they often form rather large aggregations. Many of our readers do not understand what fireflies look like, since they are difficult to see during the day: they rest on the stalks of plants or on the ground, and at night they lead active lives.

The nature of the food also differ in different types of fireflies. The herbivorous, harmless bugs feed on nectar and pollen. Predatory individuals attack spiders, ants, snails and centipedes. There are species whose adults do not eat at all, they do not even have a mouth.

Why do the fireflies glow?

Probably, many people in their childhood, resting with their grandmother or in a camp on the Black Sea coast, see how fireflies flash in the evening when it gets dark. Children love to collect unique insects in jars, and admire how fireflies glow. The organ of luminescence of these insects is photophore. It is located in the lower part of the abdomen and consists of three layers. The lowermost one is mirror. It can reflect light. Upper - this is a transparent cuticle. In the middle layer are photogenic cells that produce light. As you guessed, in its structure, this body resembles a flashlight.

Scientists call this type of luminescence bioluminescence, which results from the combination of oxygen cells with calcium, the luciferin pigment, the ATP molecule, and the enzyme luciferase.

What light emit fireflies?

Unlike electric lamps, where most of the energy flows into useless heat, with efficiency not exceeding 10%, the fireflies transfer up to 98% of the energy to light. That is, it is cold. The luminescence of these bugs is attributed to the visible yellow-green part of the spectrum, corresponding to wavelengths up to 600 nm.

Interestingly, some types of fireflies can increase or decrease the intensity of light. And even radiate intermittent glow. When the insect's nervous system gives a signal to “turn on” the light, oxygen actively enters the photophore, and when it stops feeding, the light “turns off”.

And yet, why do the fireflies glow? After all, not in order to please the eyes of man? In fact, bioluminescence for fireflies is a means of communication between males and females. Insects do not easily signal their location, but they also distinguish their partner by the flicker frequency. North American and tropical species often perform choral serenades for their partners, flashing and fading at the same time with the whole flock. A group of the opposite sex responds with the same signal.


When the mating period comes, the male firefly is in a continuous search for a sign from its second half, ready to continue the genus. As soon as he finds him, he goes down to the chosen one. Different types of fireflies emit light at different frequencies, and this, in turn, ensures that only representatives of the same species mate with each other.

Partner selection

In fireflies reigns matriarchy - partner chooses a female. It determines it by the intensity of the glow. The brighter the light, the higher the frequency of its flicker, the male is more likely to charm the female. In tropical forests, during collective "serenades", trees shrouded in such necklaces shine brighter than shop windows in megalopolises.

Recorded cases and marriage games with a fatal outcome. The female, using a light sign, attracts males of a different species. When the unsuspecting fertilizers are, the cunning temptress eats them.

After fertilization, larvae appear from eggs laid by the female. What do firefly larvae look like? Quite large, voracious, black-colored worms with clearly visible yellow spots. Interestingly, they shine like adults. Closer to autumn, they hide in the bark of trees, where they spend the winter.

The larvae develop slowly: in the species living in the middle zone, the larvae hibernate, and in most subtropical species they grow for several weeks. The pupal stage lasts up to 2.5 weeks. The next spring, the larvae pupate and from them develop new adult individuals.

Interesting Facts

  • The firefly, radiating the brightest light, lives in the tropics of America. It reaches a length of five centimeters. And it glows, except for the abdomen, also the chest. Its light is 150 times brighter than the European relative.
  • Scientists were able to identify the gene that affects the glow. It was successfully introduced into plants, and as a result it was possible to get plantations glowing at night.
  • Residents of tropical settlements used these bugs as a kind of fixtures. The bugs were placed in small containers and such primitive lanterns illuminated the dwellings.
  • Every year at the beginning of summer in Japan the firefly festival takes place. Spectators in the garden near the temple come with the onset of twilight and with delight watching the unusually beautiful flight of a huge number of luminous bugs.
  • In Europe, the most common type is the common firefly, which is called the Ivanov worm. This unusual name for the bug was due to the belief that it glows on the night of Ivan Kupala.

We hope that you received answers to the questions, what the firefly looks like, where it lives and what kind of lifestyle it leads. These interesting insects have always aroused great human interest and, as you can see, quite reasonably.


Externally, the firefly insect looks very modest, even inconspicuous. The body is elongated and narrow, the head is very small, the antennae are short. The size of the insect firefly is small - on average, from 1 to 2 centimeters. Body color is brown, dark gray or black.

Many species of beetles have pronounced differences between the male and the female. Insect fireflies males resemble cockroaches in appearance; they can fly, but do not glow.

The female looks very similar to a larva or a worm, she does not have wings, so she leads a sedentary lifestyle. But the female is able to shine, what attracts representatives of the opposite sex.

Why shines

The glowing sweelorgan near the insect firefly is located in the back of the abdomen. It is a cluster of light cells, photocytes, through which multiple tracheas and nerves pass.

Each such cell contains the substance luciferin. While breathing through the trachea, oxygen enters the luminous organ, under the action of which luciferin is oxidized, releasing energy in the form of light.

Due to the fact that through the light cells pass the nerve endings, the firefly insect can independently regulate the intensity and mode of emission. This may be a continuous glow, blinking, ripple or flash. Thus, glowing in the dark bugs resemble the Christmas garland.


The female beetle lays eggs on a bed of leaves. After some time, black and yellow larvae appear from the eggs. They are distinguished by an excellent appetite, in addition, the firefly insect is luminous if disturbed.

Beetle larvae winter in the bark of trees. In the spring, they leave the shelter, feed heavily, then pupate. After 2 - 3 weeks, adult fireflies appear from the cocoon.

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Why do fireflies glow?

Most members of the firefly family are known for their ability to emit a phosphorescent glow, which is especially noticeable in the dark. In some species, only males can glow, in others - only females, in the third - both those and others (for example, Italian fireflies). Males emit a bright light in flight. Females are sedentary and usually glow brightly on the soil surface. There are also fireflies, which do not have this ability at all, and in many species, the light comes even from larvae and eggs.

By the way, few land animals generally possess the phenomenon of bioluminescence (chemical luminescence). Capable of this are the larvae of fungus mosquitoes, springtails (collembola), fire flies, horse spiders, and representatives of beetles, for example, such as fire-bearing crackers (pyroforuses) from the West Indies. But if we count the sea creatures, the luminous animals on Earth are at least 800 species.

Author photo: Nevit Dilmen, CC BY-SA 3.0

The organs that allow the fireflies to emit rays are photogenic cells (lanterns) that are abundantly interwoven with nerves and trachea (airway tubes). Externally, lanterns look like yellowish spots on the underside of the abdomen, covered with a transparent film (cuticle). They can be located on the last segments of the abdomen or evenly distributed over the body of the insect. Under these cells lie others, filled with uric acid crystals and capable of reflecting light. Together, these cells work only if they have a nerve impulse from an insect brain. Oxygen through the trachea enters the photogenic cell and with the help of the enzyme luciferase, which accelerates the reaction, oxidizes the compound of luciferin (light-emitting biological pigment) and ATP (adenosine triphosphate). Due to this, the firefly glows, emitting light of blue, yellow, red or green.

Males and females of the same species most often emit rays of a similar color, but there are exceptions. The color of luminescence depends on the temperature and acidity (pH) of the environment, as well as on the structure of luciferase.

Photogenic cells. Photo by: National Park Service, Public Domain

The beetles themselves regulate the glow, they can strengthen or weaken it, make it intermittent or continuous. Each species has its own unique system of phosphoric radiation. Depending on the purpose, the glow of fireflies can be pulsating, blinking, stable, fading, bright or dim. The female of each species responds only to the signals of the male with a certain frequency and intensity of light, that is, his mode. By the special rhythm of light emission, beetles not only attract partners, but also scare off predators and protect the borders of their territories. There are:

  • male search and call signals,
  • consensus, refusal and post-cudative signals in females,
  • signals of aggression, protest and even light mimicry.

Interestingly, the fireflies spend about 98% of their energy on emitting light, whereas an ordinary electric bulb (incandescent lamp) turns only 4% of energy into light, the rest of the energy is dissipated as heat.

Daylight fireflies, often do not need the ability to emit light, because it is absent from them. But those representatives of the day who live in caves or in dark corners of the forest, also include their own "lanterns". Eggs of all kinds of fireflies also emit light at first, but it soon fades away. In the afternoon, the light of the firefly can be noticed if you cover the insect with two palms or move it to a dark place.

By the way, the fireflies also give signals using the flight direction. For example, representatives of one species fly in a straight line, representatives of another species fly a broken line.

Firefly Lamprohiza splendidula. Photo author: Kryp, CC0

Types of light signals of fireflies

All the light signals of the fireflies VF Bak divided into 4 types:

  • Continuous glow

So glow adult beetles belonging to the genus Phengodes, and the eggs of all fireflies, without exception. Neither ambient temperature nor illumination influence the brightness of the rays of this uncontrollable type of glow.

  • Discontinuous glow

Depending on the environmental factors and the internal state of the insect, it can be a weak or strong light. It may fade completely for a while. So shines most of the larvae.

This type of luminescence, in which the periods of emission and the absence of light are repeated at regular intervals, is characteristic of tropical genera Luciola and Pteroptix.

There is no time dependence between the intervals of flashes and their absence with this type of glow. This type of signal is characteristic of most fireflies, especially in temperate latitudes. Under the conditions of this climate, the ability of insects to emit light strongly depends on environmental factors.

HA. Lloyd also highlighted the fifth type of glow:

This type of light signal represents a series of short flashes (frequency from 5 to 30 Hz) appearing directly one after another. It is found in all subfamilies, and its presence does not depend on the location and habitat.

Photo by: David Evans, CC BY 2.0

Firefly communication systems

In lampirids, 2 types of communicative systems are distinguished.

  1. In the first system, an individual of the same sex (more often a female) emits specific calling signals and attracts a representative of the opposite sex, for whom the presence of their own light organs is not obligatory. This type of communication is characteristic of the fireflies of the genera Phengodes, Lampyris, Arachnocampa, Diplocadon, Dioptoma (Cantheroidae).
  2. In the system of the second type, individuals of the same sex (most often flying males) emit calling-up signals, to which non-flying females give sex- and species-specific answers. This method of communication is peculiar to many species of the subfamilies Lampyrinae (genus Photinus) and Photurinae living in North and South America.

This division is not absolute, as there are species with an intermediate type of communication and with a more advanced interactive glow system (in European species Luciola italica and Luciola mingrelica).

Author photo: Kristian Pikner, CC BY-SA 4.0

Synchronous flash of fireflies

In the tropics, many species of beetles from the family Lampyridae seem to shine together. They simultaneously light their "lanterns" and at the same time extinguish them. Scientists called this phenomenon the synchronous flashing of fireflies. Процесс синхронного вспыхивания светлячков до конца ещё не изучен, и есть несколько версий касательно того, как насекомым удается светить одновременно. По одной из них, внутри группы жуков одного вида есть лидер, он и служит дирижёром этого «хора». А так как все представители знают частоту (время перерыва и время свечения), у них получается делать это очень дружно. Синхронно вспыхивают, в основном, самцы лампирид. Причем все исследователи склоняются к версии, что синхронизация сигналов светляков связана с половым поведением насекомых. За счёт увеличения плотности популяции у них повышается возможность найти партнёра для спаривания. Также ученые заметили, что синхронность света насекомых можно нарушать, если повесить рядом с ними лампу.But with the termination of its work, the process is restored.

The first mention of this phenomenon dates back to 1680 - a description that E. Kampfer made after traveling to Bangkok. Later, many statements were made about the observation of this phenomenon in Texas (USA), Japan, Thailand, Malaysia and the mountainous regions of New Guinea. Especially many of these types of fireflies live in Malaysia: there the local residents call this phenomenon “kelip-kelip”. In the US, in the Great Smoky Mountains National Park, visitors are watching the simultaneous luminosity of members of the Photinus carolinus species.

Author photo: Mike Lewinski, CC BY 2.0

Where do the fireflies live?

Fireflies are fairly common, heat-loving insects that inhabit all parts of the world:

  • in North and South America,
  • in Africa,
  • in Australia and New Zealand,
  • in Europe (including the UK)
  • in Asia (Malaysia, China, India, Japan, Indonesia and the Philippines).

Most fireflies are found in the Northern Hemisphere. Many of them live in warm countries, that is, in tropical and subtropical areas of our planet. Some species are found in temperate latitudes. In Russia, there are 20 species of fireflies that can be found throughout the whole territory, except the north: in the Far East, in the European part and in Siberia. They can be found in deciduous forests, in swamps, rivers and lakes, in glades.

Fireflies do not like to live in groups, they are loners, but they often form temporary clusters. Most of the fireflies are nocturnal animals, but there are also those that are active during daylight hours. During the day, insects rest on the grass, hiding under bark, stones, or in silt, and at night, those that are able to fly do it smoothly and quickly. In cold weather, they can often be seen on the surface of the earth.

Author photo: ForestWander, CC BY-SA 3.0 us

What do the fireflies eat?

Both larvae and adults are more often predators, although there are fireflies that feed on nectar and pollen of flowers, as well as decaying plants. Carnivorous bugs prey on other insects, caterpillars of scoop butterflies, mollusks, centipedes, earthworms, and even their fellows. Some males living in the tropics (for example, from the genus Photuris), after mating, imitate the rhythm of the glow of males of another species in order to eat them and get nutrients for the development of their offspring.

Females in the adult state feed more often on males. Many males do not eat at all and die after several matings, although there are other data according to which all adults eat food.

The firefly larvae on the last segment of the abdomen have a retractable brush. She is needed in order to clean off the mucus that remains on her little head after eating snails and slugs. All firefly larvae are active predators. Basically, they eat mollusks and often live in their hard shells.

Author photo: Heinz Albers,, CC BY 2.5

Types of fireflies, photos and titles.

In total, entomologists have about 2000 species of fireflies. Let's talk about the most famous of them.

  • Common Firefly (the same big firefly) (lat. Lampyris noctiluca) It has popular names Ivanov the worm or the Ivanovo worm. The appearance of the insect was associated with the holiday of Ivan Kupala, since it is with the arrival of summer that the firefly begins the mating season. This is where the national nickname came from, which was given to a female, very similar to a worm.

The big firefly is a bug with a firefly appearance. The size of males reaches 11-15 mm, females - 11-18 mm. The insect has a flat, villous body and all other signs of the family and order. Male and female of this species are very different from each other. The female is similar to a larva and leads a sedentary land-based lifestyle. Both representatives of the sex have the ability to bioluminescence. But in the female it is much more pronounced, in the twilight it gives off a rather bright glow. The male flies well, but glows very faintly, almost imperceptibly to observers. Obviously it is the female who gives the signal to the partner.

Male. Author photo: Miroslav Fiala

Female. Author photo: Morten DD Hansen, Public Domain

  • Firefly (lat. Luciola cruciata) - the usual inhabitant of rice fields of Japan. Lives only in wet silt or directly in the water. She hunts mollusks at night, including intermediate hosts of worm-flukes. During the hunt, it shines very brightly, radiating blue light.

Author photo: harum.koh, CC BY-NC-SA 4.0

  • Common Eastern Firefly (Fiery Photus) (Latin: Photinus pyralis) lives on the territory of North America. Males from the genus Photinus glow only on takeoff and fly along a zigzag path, and females use imitative illumination to eat males of other species. Of the representatives of this kind of American scientists emit the enzyme luciferase, to use it in biological practice. The common eastern firefly is the most common in North America.

This is a night beetle, having a dark brown body with a length of 11-14 mm. Due to the bright light, it is clearly visible on the soil surface. Females of this species look like worms. Fire photinus larvae live from 1 to 2 years and hide in wet places - near the streams, under the bark and on the ground. They spend the winter buried in the ground.

Both adult insects and their larvae are predators, they eat worms and snails.

Author photo: Katja Schulz, CC BY 2.0

  • Pennsylvania Firefly (Latin Photuris pennsylvanica) lives only in Canada and the United States. The adult beetle reaches a size of 2 cm. It has a flat black body, red eyes and yellow underlays. On the last segments of his abdomen are photogenic cells.

The larva of this insect was called the "luminous worm" for its ability to bioluminescence. Worm-like females of this species also have the ability to light mimicry; they imitate the signals of the Photinus fireflies to capture and eat their males.

Author photo: Gould363, CC BY-SA 4.0

  • Cyphonocerus ruficollis - the most primitive and poorly studied type of fireflies. It lives in North America and Eurasia. In Russia, the insect is found in Primorye, where females and males actively glow in August. The beetle is listed in the Red Book of Russia.

Photo author: Dysmorodrepanis, CC BY-SA 2.0

  • Red Firefly (pyrocelium firefly) (Latin Pyrocaelia rufa) - a rare and poorly studied species that lives in the Far East of Russia. Its length can reach 15 mm. It is called the red firefly because its scute and rounded pronotum have an orange tint. The beetles are dark brown, the antennae are piloid and small.

The larval stage of this insect lasts 2 years. You can find a larva in the grass, under stones or in the forest floor. Adult males fly and shine.

  • Firefly fir (lat. Pterotus obscuripennis) - a small black beetle with an orange head and a saw-like antennae (bunches). Females of this species fly and shine, males lose their ability to emit light after becoming an adult insect.

Firefly beetles live in the forests of North America.

Author photo: Judy Gallagher, CC BY 2.0

  • Central European worm (glowing worm) (Latin: Lamprohiza splendidula) - the inhabitant of the center of Europe. The pronotum of the male beetle has clear transparent spots, and the rest of its body is colored light brown. The length of the body of the insect varies from 10 to 15 mm.

Males are especially bright in flight. Females are worm-shaped and can also emit bright light. The organs of light production are located in Central European worms not only at the end of the abdomen, but also in the second breast segment. Larvae of this species can also glow. They have a black hairy body with yellow-pink dots on the sides.

Photo author: Kryp, CC0

The benefits and harm of fireflies

Fireflies are beneficial insects. They destroy the intermediate hosts of parasitic flatworms - mollusks and slugs. Like fairy elves, they beautifully illuminate the area where they live. Scientists use them to isolate substances that can determine the existence of life on other planets and to create new organisms.

Fireflies have very few enemies, since insects produce poisonous or unpleasant taste substances belonging to the lucibuphagin group and frightening predators.

Firefly Ellychnia corrusca. Author photo: Katja Schulz, CC BY 2.0