Fireflies also called lightning bugs are members of Lampyridae, a family of insects within the beetle order Coleoptera, or winged beetles.
There are about 2,000 firefly species.
Fireflies are found on every continent except Antarctica.
These insects live in a variety of warm environments, as well as in more temperate regions, and are a familiar sight on summer evenings.
Fireflies thrive in forests, fields and marshes near lakes, rivers, ponds, streams and vernal pools. They need a moist environment to survive.
Fireflies are beetles that range from 5 to 25 milometers (0.2 to 1 inch) in length.
Fireflies tend to be brown or black and soft-bodied, often with the elytra, or front wings, more leathery than those of other beetles. Although the females of some species are similar in appearance to males, larviform females are found in many other firefly species. These females can often be distinguished from the larvae only because they have compound eyes.
Most species of fireflies are nocturnal, although some species are diurnal (active during the day). Most diurnal species are not luminescent; however, some species that remain in shadowy areas may produce light.
Fireflies produce a chemical reaction inside their bodies that allows them to light up. This type of light production is called bioluminescence. The method by which fireflies produce light is perhaps the best known example of bioluminescence.
Fireflies contain a chemical in their abdomen called luciferin. When that chemical combines with oxygen and with an enzyme called luciferase, the ensuing chemical reaction causes their abdomen to light up.
Unlike a light bulb, which produces a lot of heat in addition to light, a firefly’s light is cold light, without a lot of energy being lost as heat. This is necessary because if a firefly’s light-producing organ got as hot as a light bulb, the firefly would not survive the experience.
Although the most typical color for firefly light is a luminous yellow-green, the various species of fireflies can also produce green, yellow, orange, and red light.
Firefly lights are the most efficient lights in the world — nearly 100% of the energy in the chemical reaction is emitted as light. Compare that to your average light bulb, which produces 90% of its energy as heat, and only 10 percent as light.
Only light in the visible spectrum is emitted – there are no infrared or ultraviolet frequencies.
Like all beetles, fireflies undergo complete metamorphosis with four stages in their life cycle: egg, larva, pupa, and adult.
A few days after mating, a female lays her fertilized eggs on or just below the surface of the ground. The eggs hatch three to four weeks later, and the larvae feed until the end of the summer. Fireflies hibernate over winter during the larval stage. Some do this by burrowing underground, while others find places on or under the bark of trees. They emerge in the spring. After several weeks of feeding on other insects, snails and worms, they pupate for 1 to 2.5 weeks and emerge as adults.
The average lifespan of adult firefly is approximately 2 months.
Adult fireflies diet varies: some are predatory and feed on insects, while others feed on plant pollen or nectar. Some, like the European Glowworm beetle, have no mouth because they not need to eat during their adult life stage.
Bioluminescence serves a different function in larvae than it does in adults.
It appears to be a warning signal to predators, since many firefly larvae contain chemicals that are distasteful or toxic. Most fireflies are quite distasteful to eat and sometimes poisonous to
vertebrate predators.
Light in adult beetles was originally thought to be used for similar warning purposes, but now its primary purpose is thought to be used in mate selection.
Firefly light is usually intermittent, and flashes in patterns that are unique to each species. Each blinking pattern is an optical signal that helps fireflies find potential mates.
Both male and female fireflies turn on their lights when choosing a mate, and use their blinking lights as a means to communicate during courtship.
Typically, the females sit immobile, and only flash back when they see a male with a particularly impressive display.
Fireflies also use light to attract prey.
Female fireflies in the genus Photuris employ a technique called “aggressive mimicry” to lure and then eat other fireflies.
Called “simultaneous bioluminescence” by scientists, the phenomenon of fireflies flashing in unison only happens in two places in the world: southeast Asia and the Great Smoky Mountains National Park in Tennessee.
Not only do fireflies taste nasty, they can actually kill. When predators attack, fireflies kick in to a process called “reflex bleeding.” They shed drops of blood that contain bitter-tasting chemicals that are poisonous to vertebrates.
When scientist Marc Branham with the American Museum of Natural History gently put a firefly he’d caught in a net between his lips (his hands were full with a jar), “Both lips went numb. Then my throat constricted. They really taste sort of astringent. I quickly put them into my jar and I haven’t done that since.”
Bats will gag and vomit if they accidentally swallow a firefly. At least one species of lizard dies after eating fireflies. Mammals and birds also gag on the taste, and throw up.
But the firefly doesn’t get a free pass. Toads and frogs don’t seem to be affected by the taste, and will gobble them up. And spiders spinning a web will be glad to put an end to the firefly’s cocky attitude as well.