Why do fireflies glow?

A firefly is a soft, completely metamorphosed beetle with a somatic winged sheath that lasts through four periods of egg, larva, pupae, and adult. There are about 2,000 species of fireflies worldwide. Currently known fireflies species, their larvae will emit light, generally the larval luminous apparatus is located on both sides of the eighth abdominal segment, when nocturnal activity emits light. Whether adults emit light depends on the species; for example, in the genus Drilaster, although the larvae emit light, neither male nor female adults emit light.

The glow of fireflies, in simple terms, is a series of complex biochemical reactions that occur under the catalysis of luciferin, and light is the energy released in this process. Because different species of fireflies have different types of glow, isolation is naturally formed between species. The vast majority of species of fireflies are males with light emitters, while females have no light emitters or are less developed. Although most of the fireflies we have of are males with two luminaries and females with one luminous apparatus, this only occurs in the subfamily Luciola and Curtos. Because like the Taiwanese window fireflies (Pyrocoelia analis), both male and female have two luminaries, the biggest difference between the two is that the female is short-winged, while the male is long-winged.

The glower of a firefly is composed of luminous cells, reflex layer cells, nerves and epidermis. If the structure of the light emitter is likened to the lamp of the car, the light-emitting cells are like the bulbs of the lamps, and the reflective layer cells are like the lampshades of the lamps, which will reflect the light emitted by the light-emitting cells in a concentrated way. So although it is only a small light, it feels quite bright in the dark.

The glowworm's luminescence apparatus emits light, starting with nerve impulses transmitted to the light-emitting cells, so that the fluorescein that was originally in a state of inhibition is released. The glowing cells of fireflies have a phosphorus-containing chemical called fluorescein, which is catalyzed by fluorescein, and the energy produced is released in the form of light. Since most of the energy generated by the reaction is used to emit light, only 2 to 10% of the energy is converted to thermal energy, so when the fireflies stop at our hands, we will not be burned by the light of the fireflies, so some people call the light emitted by the fireflies "cold light".

As for the purpose of fireflies to emit light, the hypothesis proposed by early scholars has functions such as courtship, communication, illumination, warning, display, and regulation of populations; but in addition to courtship and communication, other functions are only the results of scientists' observations, or only speculation. Only in recent years, some scholars have verified the warning: in 1999, the scholar Knight et al. found that lizards that mistakenly ate fireflies adults would die, confirming that the luminescence of adult insects in addition to finding mates also had the effect of warning other organisms; scholars Andrewood et al. in 1997 experimented with mice, confirmed that the glow of larvae has a warning effect on mice.

The glowing behavior of fireflies at night, taking the black-winged firefly (Luciola cerata) as an example, the current study found that most of the males began to fly brightly on the perch after sunset; soon after the males began to be active, the females began to appear in the high places around the habitat (the females also emit light, but only one luminous device section, and the males have two luminescents), from 7 p.m. to about 11:30 p.m., hundreds of fireflies can be seen glowing in their habitat, but almost after 11:30 p.m., The adults gradually stop glowing. And the frequency of male insect light also changes, not all night the same frequency of light.