Medflies (果蝇) are a big headache for farmers worldwide. They can lay their eggs in over 300 kinds of fruits and vegetables. The worst thing is that when they make their way into an area, it is hard to keep the products free of them.
Medflies lay eggs inside the poor fruits or vegetables. When the eggs break, they turn into worms that can seriously damage the products. The problem is that it can be hard to know that the flies are there until it's too late. The fruits and vegetables still look normal even after the eggs are laid inside. Once the damaged fruits and vegetables are sent to other places, the Medflies spread and reproduce at a surprisingly fast speed.
In the 1980s, three Medflies were found on a farm in California. To stop the problem from spreading, the local government set up a quarantine area (隔离区) where no fruits, nuts, or vegetables can be moved out. Meanwhile, it developed a program to keep Medflies under control. The plan involved using planes to spread millions of male Medflies out over the area. According to the scientists, these Medflies all have been treated with a special method to make sure that they can't help produce new Medflies. That means even though new eggs are laid, they will never grow.
Dropping millions of Medflies sounded like a bad idea, but to everyone's surprise, the program worked well. The government says the number of Medflies in California has shrunk by over 90%. Now we can fight Medflies with Medflies!
① Worms damage fruits. ② Medflies lay eggs inside fruits.
③ Worms come out of eggs. ④Damaged fruits are moved to other places.
