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How fireflies glow – and which signals they send


You may not be able to see what you think you saw when you first saw it. But you stare at & # 39; a flash of light and there it is again – the first firefighter from & # 39; If you are in a good four-way habitat, it's already dozens, or even hundreds, of the insects flying over it, and its mysterious signals fly.

Fireflies – alternatively known as lightnings in many of the United States – are still flying bugs. They are soft-winged beetles, related to click-heads and others. The most dramatic aspect of their biology is that they can produce light; this ability in a living organism, called bioluminescence, is relatively rare.

I am an entomologist that researches and learns about ecology and biology of insects. Recently I tried to understand the diversity and ecology of fireflies in my home state of North Carolina. Fireworks are widely found in North America, including many places in the west, but they are the most abundant and diverse in the eastern half of the continent, from Florida to southern Canada.

Bioluminescent beetles

A chemical reaction in the stomach of & # 39; a beetle gives her bioluminescence.
Cathy Keifer /

Fireworks produce light in special organs in their abdomen by a combination of a chemical called luciferin, enzymes called luciferases, oxygen and cellular fuel, ATP. Entomologists think they control their blinking by regulating how much oxygen goes to their light-producing organs.

Fireflies have probably evolved as a means of removing predators, but now they mostly use this ability to find measurements. Interestingly, not all fireflies produce light; There are several types that fly daily and apparently rely on the odors of pheromones to find each other.

Each firefly-type has its own signal system. In most North American species, the men fly to & # 39; a high altitude, in the correct habitat and at & # 39; e real time from the night before them, and flash a unique unique signal. The females are at a soil or vegetation, looking for men. As a female, one sees that makes her kind of signal – and that does well – she flies back with a kind of flash of her own. Then the two reciprocate signaling as the man flies to her. If everything goes well, say it.

A good example is Photinus pyralis, a regular backdrop that is often called the Big Dipper. A man flies to twilight about 3 meters from the ground. Every five seconds or so he makes a one-second flash as he flies into & # 39; the form of an & # 39; J. & # 39; The Female Photinus pyralis is in low vegetation. If she sees a guy who likes it, she waits two seconds before she makes a third second of her own flash at the third second.

Some species can "call" a lot of hours a night, while others still only shine for 20 minutes. Fire-light communication can become much more complicated; Some types have multiple signal systems, and some may use their bright organs for other purposes.

Some Tennessee fireflies put on a synchronized show.

While most male fireflies do their own thing and independently flash of other men of the same kind, they are the ones that sync them flashes when they're many others. In North America, the two most famous species are these, Photinus carolinus from the Appalachian Mountains, including the Great Smoky Mountains National Park, and the Photuris frontalis light up places like Congaree National Park in South Carolina.

In both these types, scientists think that men synchronize, so everyone has the opportunity to search for females, and for females to signal males. These displays are spectacular, and the stool of people who want to see them at the most famous locations has made it necessary to perform a lottery for viewing them. Both types, however, represent a wide geographical range, and it would be possible to look at other, less steep areas.

Smelly chemical defense works

Many fireflies protect themselves against predators with chemicals called lucibufagins. These are molecules that do not synthesize the insects of other chemicals they eat in their diets. Lucibufagins are related in common with the poisons that are emitted on their shine, and while they are poisonous in some doses, they are also extremely innocuous.

Birds and other predators soon learn to avoid birds. I have seen a path on my back porch eating a fire and spit it out immediately; the insect ran away, threw, but apparently disaster. A colleague of mine once put a firefighter in the mouth – and his mouth stumbled for an hour!

Mating Photinus pyralis.
Clyde Sorenson, CC BY-ND

Many other insects visually imitate fireflies to reap the benefit of something unpleasant to eat and poison. Firework also appears to produce other defensive chemicals, some of which may contribute to their distinctive fragrance.

Much Photuris fireflies cannot produce these defective chemicals. That the females of these large, long-legged lightning bugs do something surprising: once they are mated, they begin to ignore the flashes of women Photinus and then the men eat you & # 39; t react. These femme fatales use the lucibufagins that they get by eating their heavily disappointed proai to protect themselves and their eggs from predators. They transmit the chemicals quickly to their blood, and bloom spontaneously as a predator seizes.

When fireflies get rid of a pocket fan habitat, they are unlikely to return.
Fer Gregory /

No place like home

Most fireflies are habitat specialists, using forests, meadows and salt marshes. They trust that habitat will remain unrestrained for the year or more than it will complete their lives. These insects spend most of their lives as larvae that are prey to earthworms and other animals in soil or bladder – most adults do not feed at all. If this habitat has been disturbed during its youth, populations can remain.

Adding to this vulnerability is the fact that the females are of many kinds – such as the famous blue ghosts of the Southern Appalachians and elsewhere – are wingless and can no longer spread than they can walk. If a population of blue ghosts is destroyed by logging or other disturbance, it will not reset. Habitat destruction is therefore one of the biggest threats to fireflies. Other hazards include lightening of artificial lights and perhaps insecticide applications for mouse control.

It's still a lot to learn about fireflies. Entomologists like me have identified about 170 species in North America, but it is clear that many more species are present here. Encourage your attention to the firefly; observe their flash patterns and behavior. Perhaps you discover one of these new species.

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