The purple loosestirfes are a beautiful wild plant. They are native of Eurasia, more specifically Macedonia, and they have been brought by accident in North America. Once there, this plant managed to spread out very quickly in the wetlands, rapidly overtaking the territory of the native species. The problem became very serious, especially in Michigan, so the scientists from the universities started to make projects in order to stop this invasive species from destroying the local flora and even fauna. The biggest steps made have been by releasing natural enemies of this plant where it has spread out. The natural enemies are all insects, and they have selectively been released to be only harmful tot he purple loosestrife, but not the other plants. The effects have been good, as the insects managed to reduce the density of this invasive species by a lot, opening up space for the native species to thrive again.
Source: Michigan State University