No wonder people use to believe in “spontaneous generation”—the theory that insects and other small living things can arise from dead matter without going through a cycle of birth, reproduction and death. Fruit flies (Drosophila) were thought to come from rotting meat. In 1859, Louis Pasteur, a French scientist, debunked this theory. His laboratory experiments proved that fruit flies mated and had tiny offspring just like other living things.
Fruit flies spend their whole lives on decaying fruits and vegetables. Mama Drosophila lays her eggs on a piece of fruit, they hatch there, and her offspring eat their bedding. Nature gave them the perfect mouth for extracting moisture from fruit flesh. Because their eyesight is excellent, they can see danger approaching. Even a shadow cast across the kitchen counter spooks them. Off they fly, zigzagging out of reach.
Wikipedia calls fruit flies “major pests in the world.” The only way to escape them is to move to Antarctica.
Fruit flies aren’t completely useless. They help genetic researchers study inherited diseases. Over half of the diseases afflicting humans have a match in the genetic code of fruit flies. Laboratory scientists always have a fresh supply on hand because Drosophila live only a few days and produce about a gazillion eggs.
* * *