In 1946, imported beetles were released against toxic St. Johnswort in northern California; by 1957, the weed had fallen to less than 1% of its former abundance

By the 1940s, European Klamathweed had established itself as a major rangeland threat in California. To combat this invasive species, leaf beetles known as Chrysolina hyperici and quadrigemina were released. Remarkably, these beetles managed to diminish the weed's presence by over ninety-nine percent within a decade. Chrysolina quadrigemina thrived, particularly in California's arid conditions, though this intervention inadvertently impacted native plants in the eastern United States.