California red scale is one of the three major arthropodpests of citrus in California, causing an annual economic crop loss of approximately $1 5 million. CRS infestations can lower the market grade of fruit as well as cause reduced tree vigor and twig and branch dieback. Management of California red scale. Aonidiella aurantii (Maskell), in the southern part of the state relies heavily on biological control with several beneficial insect parasites. Red scale is still under eradication in most southern California desert production areas. In San Joaquin Valley citrus growing areas, parasites are much less effective than in southern California and chemical control is the standard management practice. A major concern in the Valley is the potential development of pesticide resistance in California red scale, such as has been observed in Israel and South Africa. Recent research has been aimed at developing new control strategies for CRS, and at evaluating pheromone monitoring devices as a way to improve control timing and reduce the use of pesticides. The following articles report on some aspects of research funded by the Citrus Research Board, the US. Department of Agriculture, and the University of California Integra ted Pest Management Project.

This research was supported in part by the UC Statewide IPM Project. Substantial contributions to this project were made by John L. Baritelle, Thomas S. Bellows, Charles E. Kennett, Robert F. Luck, Alix A. Rhodes, Ann J. Strawn and Dicky S. Yu.