Glenn E. Askey, age 13, of Williamsport, Pa., for his question:
WHERE DO FRUIT FLIES COME FROM?
We are told that all living things come from parents like themselves. But there are times when an ordinary person finds this scientific statement hard to swallow. For instance, we may leave a half eaten apple on the table when there are no flies in sight, the doors and windows are screened. Yet, in a short while, our apple is infested with a swarm of fruit flies. We wonder where they came from.
There is the Oriental fruit fly, the Mexican fruit fly, the Mediterranean fruit fly plus dozens of others, both native and imported species. All of them are genuine flies of the insect order Diptera, a name which refers to their two gauzy little wings. Their life cycle develops through four stages ¬which accounts for their sudden arrival from nowhere.
The average adult fruit fly is a colorful creature, less than a quarter of an inch long. The life cycle begins when the female lays her mini white eggs where the hatching larvae will find plenty of their favorite food. This is sure to be some kind of fruit, and each species has its own preference. Some attack apples; others infest cherries or oranges. Almost every type of fruit has its personal fruit fly enemy.
Unless your eyes are very sharp, you are not likely to spot a batch of fruit fly eggs nestled inside a juicy peach. The little white maggots are not easy to spot, either. Though you might happen to notice the quiet little pupae because usually they are a brownish color. In any case, these early stages of the fruit fly's life often go undetected.
The wretched critters become visible when the pupae hatch and take to the air as winged insects. This is when we wonder where in the world fruit flies come from. The fact is, they were disguised as eggs, maggoty larvae and pupae cunningly concealed inside their favorite fruit.
During the summer, the life cycle of a fruit fly is completed in about two weeks. This means that many generations erupt and infest our orchards. For generations, growers have used various insecticides to keep these pests under control. However, some of the chemicals may be harmful to other living things. Growers now are turning to other methods of fruit fly control. In some cases, insect eating wasps and other fruit fly predators have been encouraged.
Perhaps the most up to date method of fruit fly control involves releasing millions more fruit flies into infested orchards. This sounds ridiculous. But these extras are sterile male flies. When they mate with the females, there will be no fruitful offspring and the fruit fly population explosions should be brought under control.