Oat Hill Mine Trail

These Biocontrol beetles (Chrysolina quadrigemina. a leaf beetle) were imported to control klamathweed (St. John's Wort). By 1944 klamathweed occupied over two million acres of rangeland in thirty counties of California. Not only were food forage plants greatly reduced but cattle and sheep lost weight when eating the weed because of its toxic effect, sensitizing them to sunlight. This resulted in such a great decrease in land values that it became almost impossible for ranchers to borrow money for development (DeBach 1974). After 10 years klamathweed was reduced more than 99%.