Illinois Department of Natural Resources

Exotic Species

Exotic species are those organisms introduced into habitats where they are not native. Invasive exotic species are organisms not native to a region, and whose introduction causes economic or environmental harm or harm to human health. In their natural habitats, these organisms developed stable populations and complex relationships with other species. When removed from the predators, parasites, diseases and competitors that have kept their numbers in check, species introduced into new habitats often overrun their new home and crowd out native species. Once established, exotic species can rarely be eliminated.

Humans are connected to most exotic species introductions. As people developed modes of transportation that allowed rapid and easy movement over long distances, they began to travel to new areas. These settlers frequently took species of plants and animals with them, either accidentally or intentionally. Some introductions did unexpected damage. Some had positive outcomes (food and horticultural crops). In North America, the list of invasive exotic species is long and includes such organisms as the gypsy moth, zebra mussel, Japanese beetle, kudzu, multiflora rose, Japanese honeysuckle and purple loosestrife. The harm from these organisms ranges from being serious pests of forests and crops to invaders of landscapes, capable of displacing native species and reducing biological diversity. Often, invasive species become ingrained in the environment before eradication efforts begin. Land managers can only try to keep them in check, as eliminating them becomes nearly impossible.

What can you do to stop the spread of exotic species? Here are some suggestions.

1. Learn to identify invasive exotic species. Find out who to contact to report new invasive species. Get help controlling invasive species on your property.

2. Don't release plants or animals into the environment.

3. Use plants native to your region for landscaping.

4. Don't bring foreign plants, animals, fruits or soils into this country without having them inspected by quarantine officials.

5. Educate yourself and others about exotic species.

6. Regarding zebra mussels: inspect all boat surfaces which have been in contact with water; and wash your boat, motor and trailer with hot water after using them, preferably at a car wash.

7. Get involved in volunteer efforts to remove invasive species from your area.