In Switzerland more and more alien plant species are making an appearance in the forests. When these species escape into the wild, and appear in large numbers, they can eliminate indigenous species, cause economic damage or affect people’s health.

In May 2009 the oriental chestnut gall wasp (Dryocosmus kuriphilus), which originates from China, was discovered in the Canton Ticino. This is the first time this invasive species has been observed in Switzerland.

For quite a while now the Asian and the Citrus Longhorned Beetles have been heading the international insect quarantine list. In 2006, an adult Citrus Longhorned Beetle and a larva of the same species were discovered in Switzerland.

It happens more and more often that new plant and animal species are involuntarily or artificially brought into new living spaces. This often has surprising effects. The forest as one of the most important cultivated surfaces in Germany is highly affected by such processes.

The Giant Hogweed is one of the most famous plants whose importation turned out to be quite problematic. For solving these problems, the "Landesbund für Vogelschutz" offers some advice based on its own experience.