The Present Status of Biological Control Work in California

Abstract

Biological control is discussed from two angles; one, that of the public attitude toward it; the other, its present condition from the economic standpoint. Because of the spectacular results of the introduction of Vedalia, the Australian ladybird, in the early days of California horticulture, the general public was inclined to favor this method of control to the exclusion of all others. This is no longer the case and while the work is generously supported both by scientific institutions and by growers organizations, it is very properly looked upon as only one arm of the defense against insects injurious to agriculture. The numerical status of the cottony cushion scale is kept below the danger line in an almost perfect way by thc work of Vedalia cardinalis and Cryptochaetum monophlebi. The contrary is true of the black scale which, although attacked by several parasites and predators, maintains a high level of abundance and is still the most important pest of citrus in the state. The attempt to find effective natural enemies of this pest is being continued. The red scale has been studied in the orient during the past 18 months and new natural enemies have been located there. Mealybug control by the production and distribution of quantities of the ladybird Cryptolaemus has been eminently satisfactory, and costs of this operation have been reduced from those of the preceding season.