An invasive species is a nonnative species (in any reproductive stage, including seed, egg, spore, or other propagule) whose introduction causes or is likely to cause economic harm, environmental harm, or harm to human health. These species grow and reproduce rapidly, causing major disturbance to the areas in which they are present.
Steve Dewey, Utah State University, bugwood.org
The majority of nonnative species, including most of our sources of food and fiber, are not harmful, and many are highly beneficial. …