Purple Loosestrife - John D. Byrd, Mississippi State University, Bugwood.org

What are Invasive Species?

Invasive species are harmful, non-native plants, animals, and pathogens that damage our economy and environment. They include species like white pine blister rust, zebra mussels, Asian gypsy moth, yellow star thistle, New Zealand mudsnails, cereal leaf beetle and Medusahead rye—organisms that threaten the interests of all Idahoans, from our recreational pursuits to our ability to help feed the nation.

Unfortunately, as worldwide commerce and travel increase, so does the threat that unwanted species will arrive in our state or spread to areas where they are not now found. Idaho is not alone in facing these threats and there is growing national awareness of the need to prevent and control invasive species.

For many people, the term “invasive species,” by itself, may not raise particularly frightening images. After all, purple loosestrife is an attractive plant growing along the edge of wet areas. West Nile virus is something that one reads about in the paper and which mostly affects horses. Most insects are simple nuisances, and weeds are something to be sprayed if they appear in your yard. Here, in Idaho, even with our outdoor, often rural lifestyle, for most there is no consistently negative image arising from either the term or from the effects of species that we would rather not have.

Invasive species include those species purposefully or inadvertently brought here and which exhibit “invasive” characteristics. This excludes introduced species that have great value. Rather “invasive species” escape their original or intended ecological niche to habitats where they may grow and spread uncontrollably. Once there, they cause harm, whether to Idaho’s economy, to human health, or to our state’s natural world, and include:

  • Pests that threaten agricultural commodities;
  • Forest pests, including those that may attack commercially valuable timber species and those that threaten shade trees found mostly in urban settings;
  • Diseases that threaten the health of humans or domestic animals and wildlife;
  • Nuisance exotic animal species that can displace or compete with native species;
  • Noxious weeds that displace ecologically or economically valuable native rangeland species or agricultural crops or threaten the integrity of streams and lakes.