Secrets of Fireflies

It's a sure sign of summer when you can see fireflies lighting up the night. So, why do fireflies give off light? It's simple! The ones flying around are the males, and the females sit in the brush and respond by flashing their lights. This is how they find each other.

Another reason for the light is that it tells birds and other insects that fireflies aren't a good meal. Like the orange color of a monarch butterfly, or the yellow stripes on a wasp, the light on the end of a firefly lets predators know to avoid eating them. The chemicals that make the light are bitter. Birds don't like to eat them, and predator insects will begin eating the head and work their way back and drop the abdomen.

A third reason why fireflies light up is to warn other fireflies of danger. Distressed insects almost always attract insects of the same species. If fireflies are caught in a spider web they will begin distress flashing to warn others. They'll do the same thing if they are caught and put in a jar. Nevertheless, frogs have been known to gorge on a summer feast of fireflies until they themselves begin to glow.

In the United States there are more than 170 species of fireflies; worldwide there are more than 1,900 known species, and they are found on every continent except Antarctica. Each species of firefly is different. For example, many species of fireflies that come out in the daytime don't have lights at all, but use their scent, or pheromones, to attract mates. In some species the females are wingless, and they rely on their lights to attract the flying males to their location.

Different species also have particular habitats that they prefer. Some are found primarily over open fields, other occur only in wooded areas, and some reside near bogs and marches. Some flash primarily at dusk and stop when it gets dark, while others don't begin flashing until later when it is very dark.

Different species of firefly can even have different colors of light. For example, the genus Photinus have a yellow flash, Photuris have a green flash, and Pyractomena have an amber flash. Part of the fun is learning to distinguish the different types of flashes.

Many firefly species tend to be found around water such as ponds, streams, marshes or even depressions, ditches, etc., that may retain moisture longer then surrounding areas. However, fireflies can also be found in very dry regions of the world as well.