We have all enjoyed the spectacle of fireflies flashing on a warm summer evening. A dark woodland edge or open meadow full of hundreds of tiny flashing lights is a magical sight indeed. But you have to wonder -what are these insects up to?
First, fireflies are not flies at all, but soft-bodied beetles in the family Lampyridae. Most of the over 100 species found in North America are luminescent, producing a chemical light that is so efficient it wastes no energy in the form of heat. One, two or three segments near the tip of the abdomen give off the light; when they are not lit they appear paler than other abdominal segments.
The luminescent fireflies are nocturnal and are active mainly around dusk. Each species inhabits a particular habitat and is active at a certain time of night. And – this is the cool part – it has its own distinctive series of flashes.
This series of flashes is like a secret code that the male fireflies use to signal the females of their species, enabling the males and females to find each other to mate. Typically, a male flashes his signal while in flight to attract a response from a female on the ground. When she signals back, the male flies to her. There are females of some species, however, that will answer the signals of other species’ males. Their mimicry entices these males to fly in for a closer look, whereupon the female captures and eats the unsuspecting male.
Firefly eggs are laid in moist soil or rotting wood and hatch in about a month. The larvae are nocturnal carnivores, eating small insects and snails. When the weather cools they burrow underground to spend the winter, emerging again in the spring. If you happen upon a firefly larva (or even an egg) you will know it since they are luminescent as well. Look for these glowworms in the evening on the ground in damp, marshy areas.