Examples of the damages caused by these so-called "invasive species" are seemingly as endless as the amount of battles waged against them.
But are all non-native species bad?
Biologist Mark Davis says no. Davis, a professor from Macalester College in St. Paul, Minnesota, believes it's time to raise the white flag against non-native species. Most non-native species, he said, are harmless -- or even helpful.
In a letter published in the journal Nature this past June, Davis and 18 other ecologists argued that these destructive invasive species -- or those non-native species that cause ecological or economic harm -- are only a tiny subset of non-native species, and that this tiny fraction has basically given all new arrivals a bad name.
Yellow starthistle already causes millions of dollars in damage to pastures in western states each year, and as climate changes, land managers can expect the problem with that weed and others to escalate.