Forty million Cryptolaemus (a Ladybird beetle, Cryptolaemus montrouzieri Muls.) are being produced annually in insectaries in Southern California and liberated systematically, ten beetles per tree, over the several thousand acres of citrus in that area, infested with the citrophilus mealybug ( Pseudococcus gahani Green:), in the successful control of that pest. In general these beetles are being made available for field liberation during the optimum months of April, May, and June, as regards their activity. Aside from the direct relation of this period to the normal seasonal development of the host mealybug, the selection of these months is based on the period of minimum rainfall, daily temperatures above 70° Far, and a sufficient similar following period to permit a natural increase in the liberated beetles, through one or more generations, to controlling numbers.