GRE Reading Comprehension: JiJing 352-GRE阅读机经352篇 - 74B861DAKWQ0TC36K

Stem borers are insect pests that often ruin North American corn crops. On some other continents, crop damage by stem borers is controlled by a certain species of wasp. Since these wasps eat nothing but stem borers, importing them into North America will keep crop damage from stem borers under control without endangering other North American insect species.