Helen E. David, age 14, of Ottawa, Ont., Canada, for her question:
HOW LONG DOES DRAGONFLY LIVE?
The dragonfly belongs to summer days and woodsy ponds, where the sun glints rainbow colors from her gauzy wings. Actually, this fragile looking creature already may be a year or more old which is older than many insects ever get to be. What's more, her family tree dates back 300 million years, when her giant ancestors were bigger than many of our birds.
A dragonfly's life begins as an egg, which her mother places in or near the water. The egg hatches into one of the hungriest larvae of the entire insect world which is quite a record. The famished creature is a nymph, a small, wingless copy of the adult winged insect.
This dragonfly nymph is a ferocious predator the terror of its watery neighborhood. It devours mosquito larvae, fish eggs and small fishes, tadpoles and any live water dweller small enough to be grabbed in its powerful jaws.
Some species have a sneaky expandable lower jaw which folds back under the legs. In a flash, it can reach out and grab a small fish.
This phase of life lasts at least a year, and in some species the aquatic larva lives two years or more. As it grows, it molts into a larger skin and finally matures. Then it climbs up a waterweed and undergoes its final transformation. The pupa skin splits down the back and the adult winged dragonfly struggles forth into the air.
At first she is a pale, fragile creature with crumpled wings. But blood is pumped in to stiffen the wings, and she dries out in the sunny air. Now she is ready to take off on those four big gauzy wings. She is a sturdy flier, and no insect can fly faster. Her top speed is 60 m.p.h. which makes her the champ.
Unlike most winged insects, she is a fierce predator, devouring moths and other insects on the wing. Much of her time is spent in aerial acrobatics over the water, where she mates and lays her eggs. Most adult dragonflies of North America live only for a few weeks. But other species in other lands live longer. In Europe, they often migrate long distances over land and sea. Some may survive the winter in warmer climates and return to live a few weeks next summer.
Most dragonflies of North America live no longer than one year. Most of this time is spent in the water as eggs or hungry nymphs. Usually the adult stage ends soon after the egg laying season. In other countries, some species may prolong life by migrating.