Non-Native Plants and Animals
For thousands of years, people have introduced plants and animals to areas where they do not normally occur. European settlers brought with them domestic animals and cultivated plants that they needed for food, medicine, and clothing. They also accidentally introduced other species.
Some non-native species become established in their new area. They can be a problem if they become invasive, competing aggressively with native species and in some cases harming or crowding out the local species.
Over the years, increasing numbers of non-native species have been invading North America from all over the world. In Illinois, introduced species have harmed many native habitats. Control measures are often limited, unavailable, or socially (and environmentally) unacceptable. Ironically, other non-native species are sometimes introduced in an attempt to control non-native species.