How Species are Introduced

Whether they are called alien, exotic, or non-native, there are over 45,000 non-indigenous species in North America. Thanks to global trade and travel, more are arriving daily. Some will survive, reproduce, and establish themselves in our ecosystems. A few of these new arrivals can become so successful that they invade and cause economic damage. Knowing how exotic species are introduced can help protect our borders and prevent the spread of undesirable pests.

What are the reasons for species introductions?

Most exotic species arrive in new places with human help. Unintentional introductions occur when exotic species hitch a ride on an airplane, contaminate agricultural products, or drive in on the tires of fire-fighting equipment. Accidental arrivals can be minimized through sanitation procedures, such as disinfecting footwear to prevent the introduction of foot-and-mouth disease. Laws that govern agricultural commerce and enforce quarantines are aimed at preventing the accidental spread of diseases, insect pests, and weed seeds.

Unfortunately, some of our biggest exotic species problems have come from purposeful introductions. Many species that were originally imported for medicinal, ornamental, or commercial use have become invasive pests.

The possibility that harmful exotic species could be intentionally released to harm our nation's food supply and ecological integrity is a serious concern. The U.S. Department of Agriculture is working with the new Department of Homeland Security to respond to the threat of "agroterrorism".

Learn more about species introductions:

How are species transported to new areas?
How many exotic species are in the Heartland?

Explore other aspects of exotic species:

What are exotic species?
What are the impacts of exotic species?
Basic ecology