In animal taxonomy, fireflies belong to the coleopteran family. This is the largest clan in the insect kingdom, with the firefly being just one of more than 300,000 types of beetles.

Among insects, the appearance of the beetle came relatively late. In its life it must pass through being an egg, hatching, and being a larva, followed by repeated molting, then pupation, until it finally metamorphoses into an adult with the capability of flying. This phenomenon is known to the academic community as "holometabolism."

Snailing across the water: The longest a firefly might live is two years. In fact, more than half of life is spent as a ground-bound larva.

Larvae may de divided into two families--water-bred and land-bred. In 1928 Japanese scholars announced that a type of water-bred insect which could be found all across that country was a unique species. Since then people have discovered that in fact there are many varieties of water-bred fireflies. Already three types are known in Taiwan, one of which is the "yellow-green firefly" which is common in the plains.

Fireflies leave their eggs in moist decaying branches, fallen leaves, or in the moss on stones. The newborn little critters appear like tiny black leeches. Water-bred larvae wriggle into the water, while their land-based brethren head into moist places to find tiny snails or spiral-shelled creatures to eat.

Flesh-eating fireflies: Because they are carnivorous, the larvae possess sharp mouths and long, powerful jaws. Just one bite lanced into the soft underbelly of a snail is enough. Then digestive juices are emitted from the mouth, breaking down the meat into a paste so that it can be sucked in.

The little insects share the food while eating in groups. In the past one could often see a dozen or so of the bugs devouring a snail at water's edge. "This avoids leaving behind rotting meat which could affect water quality," says Yang Ping-shih, a specialist in insect damage to plants at National Taiwan University. Larvae are the scavengers of wetlands. Many snails have a diet of plant stems and leaves. The firefly plays the role of the natural enemy of the snail and controls the numbers of spiral-shelled pests. It is thus seen as a "beneficial insect" by farmers.

Snails like damp places, so fireflies also mainly hang out in wet paddy fields, along streams or in wetlands. "As a result a small number of fireflies have adapted to life in the water and have become water-bred insects," says Chen Jen-chao, associate professor at the Pingtung Institute of Technology. Most insects breathe through their trachea, but water-bred larvae are like fish, and the skin has evolved gills.

The skin of the larvae contains chitin, so they need not fear solvents or heat, and can protect their bodies. But their skin does not grow as the body does, so they must pass through molting five to seven times in a lifetime.

When autumn comes, where do all the fireflies go? "Carelessly flitting about the fence/ Taking off from the edge of the well/ Coming to accompany me in my study/ When the leaves turn and autumn arrives/ I wonder where it is you go back to." In fact, the story behind the curiosity of the ancients is quite simple.

After autumn comes, larvae which have not yet matured lose some of their vitality, and pass the winter in a state of semi-hibernation. If they have passed into the pupation stage, they find some soft mud or burrow into a stream bank or dike, passing the winter in the cocoon.

When the spring winds waft by, and the weather warms a bit, they transform again and emerge from the cocoon as black or reddish-brown adults. Before the discovery of the microscope, and before "ecological observation" became popular, when our ancestors saw these insects emerge from soft earth and light up, they imagined that the firefly was a metamorphosis from rotting leaves or decaying bamboo. The saying, "On summer nights, rotting grass turns into fireflies," was a natural result of observing transformations as the weather changed from season to season.

The life expectancy of an adult is only about one month. Some only have as little as ten or so days. Thus they devote themselves single-mindedly to the continuation of the family line. The shape of the adult body is radically different from that of the larvae. The long, sharp proboscis has disappeared, and been replaced by a short, flat one. They no longer consume snails; indeed, except for dew, the vast majority of adults take no food at all.

Adults return to the soil; cocoons await new births: The female of the "Taiwan window firefly," a land-bred species, lacks even wings. Thus the male must follow the light to its source to search for a mate. The female uses virtually all of the nutrients and strength in her body to produce the eggs; one can produce 400-500 eggs in a short half a month.

Dividing eating and reproduction into two completely separate stages is a survival strategy for insects of tiny stature.

When the autumn winds send a chill up your spine, and the migratory birds are southbound again, and the air is filled with the white flowers of the mang grass, adult fireflies which have mated and produced eggs flicker, and expire one after another, while the next generation waits in the eggs or the cocoon for their turns to be born.

[Picture Caption]

The firefly is a holometabolic insect, passing through the stages of being an egg, being a larva, molting, and pupation. In the second photo a group of larvae collectively consume a spiral-shelled animal. The third photo is a larva during molting. The fourth is of adults.

(photos courtesy of Chen Jen-chao)