What Colors Do Fireflies Glow In?

When it's dark out, you might notice the conspicuous glimmering of fireflies in the air. This light comes from the ends of their tails. Their bodies are equipped with photophores -- specifically organs that can manufacture light. These organs are located on fireflies' stomachs and are made up of a combination of cells that create light and those that reflect light. The light that fireflies give off is cold, rather than hot.

Light flashing in fireflies reaches heightened activity during the insects' breeding season, which starts at the end of the summer and closes at the beginning of the fall. This is because fireflies use their lights as a way of communicating to individuals of the opposite sex for mating interactions. The males release their light to apprise females of their own species of their reproductive availability. Females can respond to the advances by glowing back, which in turn notifies the males to where they are. Fireflies can pick up on individuals from their own species based on specific sequences in their glowing lights. The sequences of the species differ in many ways, including in the duration of their gleams. While finding mates is a major motive behind their lights, fireflies often utilize them to seek out prey, too. They're even thought to occasionally employ their light to aid their eyesight.

When fireflies give off light, they do so in a handful of different colors. These colors include vivid yellow, yellowish-orange, green and yellowish-green. Fireflies from different species often glow in different colors. Fireflies that are out and about in the night often glow in green, while fireflies that are out and about toward the end of twilight often glow in yellow.

While fireflies give off intense and bright lights, their actual body coloration is decidedly more unassuming and subtle. Mature fireflies typically have black or brown bodies. This muted coloration often enables them to successfully stay low key amid their surroundings. Fireflies' physiques generally have somewhat flattened appearances. They usually grow to anywhere between one-quarter to three-quarters in length.