Fireflies produce biolumiscence through a chemical reaction, using specialized enzymes produced by the cells in their tails. The resulting light is sometimes called “cold light,” since it generates no infrared or ultraviolet rays. The mechanics of this biological feat are well understood, although the reasons are a bit more murky. The light appears to serve a range of purposes, from attracting prey to signaling potential mates.
Before delving into the details of how fireflies produce light, it may help to know what this insect actually is. Technically, they are beetles, not flies, and there are over 2,000 species in the order Lampyridae that are capable of producing light. The ubiquitous insects can be found in warm and temperate climates all over the world, and they may also be called lightning bugs or lightning worms. In some cultures, their appearance is an exciting event, and people may hold festivals to celebrate their emergence, since it often marks the start of summer.
The main chemical involved in generating their light is luciferase, an enzyme that interacts with oxygen to glow. The special enzyme is produced by the cells in the insect's tail, and they rely on a chemical called ATP to stimulate production of this enzyme. ATP regulates cell processes in all living organisms, and it serves a wide range of functions related to cell function.
Many people have noticed that some fireflies flash on and off. These flashes are actually used as signals to communicate with other bugs. Some species can mimic the signals of other species so that they can attract a source of food. The glowing light also warns predators, as luciferase does not taste very pleasant, so other animals quickly learn to avoid glowing insects, no matter how appealing they might look.
Most fireflies are nocturnal, and they often come out around dusk in a spectacular show of lights. Other species are diurnal, and some beetles in this family cannot produce light because they have adapted for life during the day. In regions with a large firefly population, some people greatly enjoy wandering around in marshes and woods as dusk, when they come out in large masses. Lightning bugs are also common features in novels about the Southern United States, where the insects can be found in large numbers on languid summer nights.