What are invasive species? 
Invasive species are plants, animals, or organisms that spread so quickly that they harm other wildlife. They are not native to Washington and are typically brought here by someone or something. Because they aren't native to Washington, natural predators often don’t exist, allowing them to spread at alarming rates. Highly destructive invasive plants are called noxious weeds and animals are called pests.
Why are invasive species a problem?
Since they often have no natural controls, invasive species can spread rapidly and displace the native species that are already there. This causes changes in the habitat and food chains that can make it harder for native species to survive. They out-compete native plants and animals for scarce resources, changing the landscape. Invasive species damage farms and forests as well as streams, lakes, rivers, and marine waters. Invasive species also harm recreation.