What are fruit flies?

These pesky midgets seem to come from nowhere. Squadrons of them may appear indoors, hovering around a bowl of juicy, ripe fruit. They are almost small enough to squeeze through the squares of a window screen. But they did not break into the house. They were brought in with the fruit.

A true fly has a wide head, huge eyes and one pair of ggauzy wings. His mouth is made for sipping and sucking and he cannot chew solid food. So he dines on plant sap, juices and other liquids. The fruit fly is a true fly. He looks like a miniature copy of his big cousin, the. house fly, though: his neat body may be green and his round eyes may be rosy red.

There are many different fruit flies, Some kinds prefer onions, some cabbages and some choose to dine on fruit. A mother fruit fly lays about 200 little white eggs, maybe on the skin of an apple hanging on a tree. Each egg hatches into a tiny white maggot, tapered at both ends. He bores into the apple and starts to dine. Next he becomes a pupa and rests inside a crisp brown shell while hs maggoty body turns into a grown up fruit fly.

Meantime, the apple may be sent to market and taken into your home. At last the pupa hatches. He flies out of his hiding place with a host of brothers and sisters. It takes only two weeks or less for fruit flies to develop from eggs and become parents.

Suppose all this brood survived and multiplied. Suppose their offspring and their offspring all survived without accidents for two months. That first mother fruit fly would have more than 200 million descendants.

But in nature, most of them get eaten by birds and other hungry animals.

Fruit flies are hard to control in fields and orchards because they multiply so fast. But for this very same reason, the busy insects are also very useful to science. They are easy to keep and feed in glass bottles and in a few weeks, a small brood will supply a scientists with thousands of different specimens to study.

One kind of fruit fly is named Drosophila, the vinegar fly: This greenish, red eyed little fellow is a great pest in our orchards. But in the laboratory, he is one of the most useful of animals. There he is used to study heredity, the science which explains why were like our parents and also different from them.

A youngster, even a young fruit fly, resembles his parents and inherits a lot of his features from them But he also inherits a host of features from countless ancestors. This makes him sliJhtly different from each of his relatives. Science uses the fast multiplying fruit fly to figure out how these features are handed down through the generations.