UC Cooperative Extension | Agricultural Experiment Station
California red scale is one of the key pests of citrus in California. This pest can damage and kill citrus trees when it attains very large populations, which is a rare occurrence. The more common economic damage results from these scale insects settling on the fruit, causing cosmetic flaws and a downgrading of the fruit. Significant economic losses from this cosmetic damage occur at much lower population densities than the high densities required to damage the trees. Consequently, there is a very low threshold for California red scale in citrus orchards. To keep populations below the threshold, growers have traditionally relied on high-volume sprays (up to 1,000 gallons per acre) of insecticides.