Features and habitat
Today, there are about 2,000 species of fireflies in nature. Their inconspicuous appearance during the day is in no way associated with the beauty that radiates from fireflies at night.
The dimensions of the insect are small, they range from 2 mm to 2.5 cm. Large eyes are visible on their small head. The body of the firefly is narrow and oblong. Their small but clearly visible antennae and body shape often cause many people to compare fireflies to cockroaches.
But this is only a slight external resemblance. Apart from this, insects have absolutely nothing in common. Different species have differently developed distinctive features between males and females. There are those that are practically no different.
And there are fireflies with particularly well-defined dimorphism. In such cases, the males have the real appearance of fireflies, and the females more closely resemble their own larvae.
There are winged fireflies that can fly perfectly, and there are also worm-like females that prefer to move less. The color of insect fireflies is dominated by black, gray, and brown shades.
The main feature of fireflies is their luminous organ. In almost all of their species, the location of these luminous “devices” is observed at the end of the abdomen. There are also fireflies that have “lanterns” that glow along their body.
All these organs have the principle of a lighthouse. With the help of groups of phytocide cells, which are in close proximity to the trochea and nerve cells, illumination is supplied to the main “lamp” on the insect.
Each such cell has its own fuel substance called luciferin. This entire complex firefly system works using insect breathing. When it is inhaled, air moves through the trachea into the organ of luminescence.
There, oxidation of luciferin occurs, which releases energy and produces light. Insect phytocides are designed so thoughtfully and subtly that they do not even consume energy. Although they don’t have to worry about this because this system works with enviable labor intensity and impact.
The CCD of these insects is equal to 98%. This means that only 2% can be wasted. For comparison, human technical inventions have an efficiency factor of 60 to 90%.
Victors over darkness. This is not their most recent and important achievement. They can control their “flashlights” without much difficulty. Only some of them are not given the ability to regulate the light supply.
Everyone else knows how to change the degree of glow, either lighting or extinguishing their “light bulbs.” This is not just a game of glare for insects. With the help of such actions they distinguish their own from strangers. Fireflies living in Malaysia are especially perfect in this regard.
Their ignition and dulling of the glow occurs synchronously. In the jungle at night, such synchronicity is misleading. It looks like someone hung a holiday garland.
It should be noted that such an amazing ability to shine in the night is not inherent in all fireflies. There are also those among them who prefer to lead a daytime lifestyle. They do not glow at all, or their faint glow is noticeable in dense forest wilds and caves.
A wide distribution of fireflies is observed in the northern hemisphere of the planet. The territory of North America and Eurasia is their favorite habitat. They are comfortable in deciduous forests, meadows and swamps.
Types of firefly light signals
V. F. Buck divided all light signals of fireflies into 4 types:
- Continuous glow
This is how adult beetles belonging to the genus Phengodes glow, as well as the eggs of all fireflies without exception. Neither external temperature nor lighting affects the brightness of the rays of this uncontrollable type of glow.
- Intermittent glow
Depending on environmental factors and the internal state of the insect, this can be weak or strong light. It may completely fade away for a while. This is how most larvae shine.
- Ripple
This type of luminescence, in which periods of light and absence of light are repeated at regular intervals, is characteristic of the tropical genera Luciola and Pteroptix.
- Flashes
There is no time dependence between the intervals of flashes and their absence with this type of glow. This type of signal is typical for most fireflies, especially in temperate latitudes. In a given climate, the ability of insects to emit light is highly dependent on environmental factors.
HA. Lloyd also identified a fifth type of glow:
- Flicker
This type of light signal is 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 credit: David Evans, CC BY 2.0
Character and lifestyle
This not entirely collective insect still most often gathers in mass aggregations. During the daytime, they are observed to sit passively on the grass. The arrival of dusk inspires fireflies to move and fly.
They fly smoothly, measuredly and quickly at the same time. Firefly larvae cannot be called sedentary. They prefer to lead a wandering lifestyle. They are comfortable not only on land, but also in water.
Fireflies love warmth. In winter, insects hide under the bark of a tree. And with the arrival of spring and after good nutrition, they pupate. It is interesting that some females, in addition to all the above advantages, also have cunning.
They know what kind of light a certain species can glow with. They also begin to glow. Naturally, the male of that species notices the familiar glow and approaches to mate.
But the male stranger who notices the trick is no longer given the opportunity to hide. The female devours it, receiving at the same time a sufficient amount of useful substances for her life and for the development of larvae. Fireflies have not yet been fully studied. There are still many scientific discoveries ahead on this matter.
Synchronized flashing of fireflies
In the tropics, many species of beetles from the family Lampyridae seem to shine together. They simultaneously light their “lanterns” and extinguish them at the same time. Scientists call this phenomenon the synchronous flashing of fireflies. The process of synchronous flashing of fireflies has not yet been fully studied, and there are several versions regarding how insects manage to shine at the same time. According to one of them, within a group of beetles of the same species there is a leader, and he serves as the conductor of this “chorus”. And since all representatives know the frequency (break time and glow time), they manage to do this very amicably. Mostly male lampyrids flash synchronously. Moreover, all researchers are inclined to believe that the synchronization of firefly signals is associated with the sexual behavior of insects. By increasing population density, their ability to find a mating partner increases. Scientists also noticed that the synchrony of insect light can be disrupted by hanging a lamp next to them. But with the cessation of its work, the process is restored.
The first mention of this phenomenon dates back to 1680 - this is a description made by E. Kaempfer after a trip to Bangkok. Subsequently, many statements were made about the observation of this phenomenon in Texas (USA), Japan, Thailand, Malaysia and the mountainous regions of New Guinea. There are especially many of these types of fireflies in Malaysia: there the locals call this phenomenon “kelip-kelip.” In the United States, in Elcomont National Park (Great Smoky Mountains), visitors watch the synchronous glow of representatives of the species Photinus carolinus.
Photo credit: Mike Lewinski, CC BY 2.0
Nutrition
These insects can easily be classified as predators. Fireflies feed on a wide variety of animal foods. They love ants, spiders, the larvae of their fellows, snails and rotten plants.
Not all fireflies are predators. Among them there are also species that prefer pollen and nectar of plants. Species of fireflies in the adult phase, for example, do not eat anything at all; they have no mouth at all. Those fireflies that deceitfully lure representatives of other species to themselves and immediately eat them have chosen the most difficult method of obtaining food.
The scientific explanation for yellow-green beacons
The ability for bioluminescence, for producing light, in these insects is primarily due to the presence of special luminescent organs, photocytes.
At the tip of the abdomen, under the transparent part of the shell, fireflies have several segments in which, under the influence of luciferase, luciferin and oxygen are mixed. The process of oxidation or breakdown of luciferin becomes the main reason why beetles emit light.
Most members of the family are capable of adjusting the brightness of an incandescent light or producing short, intermittent flashes. And some fireflies glow synchronously. The answer to the question of why bugs don’t glow all the time will be a fairly widespread opinion in the scientific world: fireflies can control the access of oxygen to the luminescence organ.
Reproduction and lifespan
The flickering of fireflies is one of their main achievements. They not only lure potential food in this way, but also attract the opposite sex. This is most observed at the beginning of the summer. Fireflies light their sparks of love and look for their partner among a huge variety of insects.
Mating doesn't take long to happen. After this, the female has the task of laying eggs in the ground. After some time, larvae emerge from the eggs. They are more like worms and are very voracious. The ability to glow is inherent in literally larvae of all species. And they are all essentially predators.
During its maturation, the larva prefers to hide among stones, in the soil and between bark. It takes a lot of time for the larvae to develop. Some need to overwinter, while other species remain in the larval stage for several years.
Then the larva transforms into a pupa, which after 1-2.5 weeks becomes a real firefly. The firefly does not live long in the forest . The average lifespan of these insects is about 90 – 120 days.
Firefly communication systems
Lampyrids have 2 types of communication systems.
- In the first system, an individual of one sex (usually 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 mandatory. This type of communication is typical for fireflies of the genera Phengodes, Lampyris, Arachnocampa, Diplocadon, Dioptoma (Cantheroidae).
- In the second type of system, individuals of the same sex (usually flying males) emit calling signals, to which flightless females give sex- and species-specific responses. This method of communication is characteristic of many species from the subfamilies Lampyrinae (genus Photinus) and Photurinae, living in North and South America.
This division is not absolute, since there are species with an intermediate type of communication and with a more advanced interactive luminescence system (in the European species Luciola italica and Luciola mingrelica).
Photo credit: Kristian Pikner, CC BY-SA 4.0
Unconventional use of natural lanterns
Looking at the bright flickering of fireflies, since ancient times people have wondered why not use them for useful purposes. The Indians attached them to moccasins to illuminate paths and scare away snakes. The first settlers to South America used these bugs as lighting for their huts. In some settlements this tradition has been preserved to this day.
In the modern world, the question of why and how fireflies acquired the ability to bioluminescence, and how their gift can be used for scientific purposes, excites the mind of more than one entomologist. Scientists, through extensive trial and error, even managed to find a gene that causes the cells of these insects to produce luciferase.
Once this gene was isolated, it was transplanted into a tobacco leaf and the seeds were sown in an entire plantation. The emerging crop glowed when darkness fell. Experiments with fireflies are not over yet: a lot of new and interesting discoveries await us.
