Post - Vedalia Period

After success of vedalia project, California continued to promote and actively support biological control. L.O. Howard, who succeeded C.V. Riley as Chief of Division of Entomology within the Federal Government, was critical of this enthusiastic support of biological control. However, in 1912 Harry S. Smith was appointed to lead biological control in California. Smith was a USDA entomologist and supporter of biological control. L.O. Howard later wrote that biological control work in California would have been stopped by the federal government had it not been for the appointment of Smith.

In 1903- California State Horticulture Commission built an insectary in San Francisco to receive and propagate natural enemies.

During 1950s -- Several insect pests were brought under successful biological control, for example the spotted alfalfa aphid. Additionally, large scale biological control of weeds was successful, e.g., Klamath Weed.

During 1970s -- Biological control of the walnut aphid and linden aphid, and cereal leaf beetle.

In the 1970s and 80s -- the alfalfa weevil was biolocally controlled in most of the northern United States.

In the 1990s one of the best examples of importation biological control has been accomplished with the cassava mealybug.