Why Do Fireflies Glow? Interesting Facts You Didn't KnowLight Pollution Facts

Aashita Dhingra
Oct 06, 2023 By Aashita Dhingra
Originally Published on Oct 14, 2021
Why do fireflies glow? A chemical called luciferin is regarded to be responsible for the light-producing ability of a firefly.
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Age: 3-18
Read time: 7.7 Min

We all have watched the magical scene of fireflies glowing in the dark in the backyard and wondered why do fireflies glow?

The answer is that certain firefly species glow because of a process called bioluminescence. A wonderful sight that you often see in your garden or backyard at night is of many fireflies lighting the place and flying all around.

Even though we call them fireflies, these summer night bugs are not flies at all. As nocturnal members, these species come from the Lampyridae family.

The origin of the word Lampyridae is Greek and it means 'to shine.' These mystical species known as lightning bugs have magically interesting lights. The light that is emitted by fireflies is considered to be the most efficient way of energy conversion to 100% light.

They can not only emit light in one color but in three colors - yellow, orange, and green. There are 2,000 species of lightning bugs! Fireflies are not actually flies, and these species are called winged beetles.

Some fireflies are carnivores and eat other kinds of firefly species. Most larvae fly bugs feed on snails, slugs, and worms.

Also one of the interesting things in this animal-insect world we can see is how the males are more flashy than females. It is the same case with fireflies too.

The male fireflies have higher flash rates as compared to female flash rates. As a result of the difference in the flash rates, there's an increased intensity in the lights produced by males. Well, all this beauty in male animals and insects and birds are to attract their mates.

Firefly light is something that is so beautiful. But due to increased light pollution and air pollution, we don’t see much of these lighting creatures around these summers.

But if you are bothered by these bugs, you may avail of professional pest control services. Find out more about insects by reading why do wasps sting and why do flies exist.

How do fireflies emit light?

These winged beetles don't produce any heat while emitting light. They produce light chemically, so there's no heat. Chemical reactions can be very interesting!

Fireflies, also known as lightning bugs, emit light because of a chemical reaction between an organic compound in fireflies' abdomens. The organic compound is luciferin. It reacts with the air around them. By mixing chemicals and oxygen, the firefly switches its night light on and off and controls its intensity, providing mood lighting for summer evenings in your backyard.

Fireflies are born with their built-in nightlights. They glow as larvae to warn predators not to eat them. Insects like fireflies contain yucky-tasting chemicals in their body.

These tastes teach most predators a lesson to not repeat to snack on them. In adult forms, fireflies flash to identify each other and to attract mates. Female fireflies lookout for the guy flies with the brightest, flashiest light displayed.

Why do fireflies glow only at night?

Fireflies are seen mostly glowing at night. Found on summer nights, they are known to light up yellow to ward off predators at night.

Also as they are nocturnal species the male bugs involve themselves in mating then too. Their individual unique flashing patterns make it easy to find their own kind of females, without wasting much energy. Did you know that firefly larvae also glow, but they glow to send signals to the predators that they taste bad?

The main purpose of lightning bugs during nights could be to attract female bugs. They use their light as a medium to ‘talk’.

Each of their beetle types has its own style or pattern of flashing lights. The larvae of the bugs are more active during the night producing short glows, which we see as blinding bioluminescence patterns on summer nights.

Another reason why we see lightning bugs more during the night is that it is time for them to showcase their bright display to find female beetles and bugs to mate with.

The night is the right time for their chemical reactions to occur. The protein (luciferin) stored by these fireflies combines with oxygen present in the air to form a new substance called oxyluciferin, with the evolution of energy in the form of lights.

Fireflies give a cold light contrary to a warm light giving light bulb.

What causes fireflies to glow?

Fireflies flash and glow. It is the product of a chemical reaction inside the bug's body that causes them to glow.  The combination of the chemical luciferin with oxygen, calcium, ATP (Adenosine triphosphate) in the presence of luciferase, a bioluminescent enzyme is what produces light in these flashing insects.

There are quite a few reasons why these insects flash their pattern of lights. Fireflies ’ glowing behavior could be connected to the light organs that are present beneath their abdomen.

At night, male fireflies fly through the region, flashing their unique blinking lights. The female fireflies normally are seen to be on the ground looking for a bright impressive male to mate.

They respond to their mate by flashing a single time, matching their mate's specific blinking light patterns. Female fireflies glow in order to respond to males' impressive light show.

Firefly blood is known to contain a defensive steroid called lucibufagins, which makes them less than tasty to their potential hunters. With a single attack, predators learn their lesson and do not attack these creatures again.

How To Make Fireflies Glow

To make these flies glow around your backyard, you can grow pine trees nearby, as it attracts these bugs. Planting flowers and growing grasses around your backyard and area is also something that attracts them to fly to your place and glow there. The glowing of these lighting bugs is a natural phenomenon of bioluminescence.

During the night you can see them glow on their own in your garden or in the woods. If you ever get a firefly to come sit in your palm and you want to make them light up, one way to do it is to close them inside your palm and slowly shake them in your hand.

This will make them glow. One thing to note is that all fireflies do not glow.

Some species of adult fireflies are not luminous. It is because they use pheromones to attract or locate female fireflies.

Usage of pheromones in these adult fireflies is scientific proof of their ancestral conditions used as sexual signals. Luminescence as a sexual signal is a newer development in the species.

If you wish to catch or collect fireflies for research purposes, it is better to put them in a big glass or plastic jar with ventilation holes and a wet paper or towel in the bottom of the jar. Once you are done with your watching, you should release them back to nature.

Did You Know...

Fireflies are some of the most magical creatures of nature. It is a joy to watch them flutter at night. The world is filled with the magic of chemical reactions. In the firefly case too, it is the work of this chemical reaction that shows the wonderful phenomenon of bioluminescence in them.

Fireflies are one of the 2,000 species which can produce their own light or bioluminescence. Not every fly can produce light. Some flies in the region of western US lack the ability to glow. A firefly's light is not only yellow. Fireflies can light up in green or orange too.

Males of this species can synchronize their flashing in some places to search and attract females. For this, they have their own pattern of light. Not only the firefly body, but their eggs can also glow. A large group of fireflies blinks together in unison sometimes.

Larvae are carnivorous and eat on snails. Some adult carnivorous flies can eat other genera of fireflies, while other adult males and females live off of nectar and pollen. Some don’t feed on anything at all.

Light is the most efficient energy source in this universe, and these fireflies do not waste any bit of their energy and produce 100% light. The light emitted by fireflies is cold light, not warm.

One of the contributions that fireflies have made to science is their chemical, luciferase. It has been proven that luciferase is pretty useful in scientific food and safety research tests.

Today, luciferase can also be made synthetically. But there are still people who depend on fireflies for them, which could be an answer to their decline. New research has found the use of nitric oxide gas, playing a role in flash control in fireflies.

Fireflies come from the Lampyridae family, which means ‘shine,’ coinciding with their lighting behavior. They warn predators with their light not to eat them, as they have a bitter chemical produced in them.

Adult fireflies live only for a couple of weeks. But the whole process of their development from egg to adult can keep them alive for about a year.

Imitation of female fireflies using flashes could actually attract male fireflies to you.

Here at Kidadl, we have carefully created lots of interesting family-friendly facts for everyone to enjoy! If you liked our suggestions for why do fireflies glow then why not take a look at why do flies love poop or glasswing butterfly facts?

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Written by Aashita Dhingra

Bachelors in Business Administration

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Aashita DhingraBachelors in Business Administration

Based in Lucknow, India, Aashita is a skilled content creator with experience crafting study guides for high school-aged kids. Her education includes a degree in Business Administration from St. Mary's Convent Inter College, which she leverages to bring a unique perspective to her work. Aashita's passion for writing and education is evident in her ability to craft engaging content.

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