June 27, 2012
What’s more magical than a firefly light show on a warm summer night? Just remember that if you catch fireflies, you can keep them in a jar (with a lid punched to let in air and a moistened paper towel on the bottom) for only a day or two before you need to set them free.
(1) There are more than 2,000 species of fireflies, a type of beetle. Despite their name, only some species produce adults that glow. Fireflies in the western United States, for example, lack the ability to produce light.
(2) Males that do glow use their flash to attract females. Each species has its own pattern of light flashing.
(3) In some places at some times, fireflies synchronize their flashing.
(4) Firefly light can be yellow, green or orange.
(5) Firefly larvae may glow, even some that live underground or under water. They use the light to communicate to predators that they aren’t tasty (they produce unpalatable, defensive steroids for protection).
(7) A few firefly species are also carnivorous as adults. They don’t eat snails, though—they eat fireflies of other genera.
(8) Fireflies are among the many species that are bioluminescent, meaning that they can produce their own light.
(9) A chemical reaction within the firefly’s light organ produces the light—oxygen combines with calcium, adenosine triphosphate (ATP—the energy-carrying molecule of all cells) and a chemical called luciferin, when an enzyme called luciferase is present.
(10) The light is the most efficient light in the world. Nearly 100
One hundred percent of the energy in the chemical reaction is emitted as light.
(11) Luciferase has proven to be a useful chemical in scientific research, food safety testing and forensic tests. It can be used to detect levels of ATP in cells, for example.
(12) When luciferase was first discovered, the only way to obtain the chemical was from fireflies themselves. Today, synthetic luciferase is available, but some companies still harvest fireflies, which may be contributing to their decline.
(13) Other factors that may be contributing to firefly decline include light pollution and habitat destruction—if a field where fireflies live is paved over, the fireflies don’t migrate to another field, they just disappear forever.
(14) Observing fireflies in your backyard can help scientists learn more about these insects and why they’re disappearing.
Sign up for our free email newsletter and receive the best stories from Smithsonian.com each week.