1939, pesticide was invented. At that time, Swiss scientist paul miller discovered that a chemical called "DDT" (dichlorodiphenyltrichloroethane) was a powerful pesticide. In Switzerland, DDT is used to control potato beetles in Colorado and to kill mosquitoes that spread malaria. During World War II, DDT was also proved to be effective in protecting the army and preventing diseases caused by pests.
Extension of knowledge points:
Insecticide (English: Insecticide. Insecticide) is mainly used to control agricultural pests and urban health pests. It has a long history of use, large dosage and many varieties. In the 20th century, with the rapid development of agriculture, pesticides greatly increased agricultural output. But almost all pesticides will seriously change the ecosystem, most of them are harmful to human body, and some will be concentrated in the food chain. We must strike a balance between agricultural development and environment and health.