Biological control of olive scale,Parlatoria oleae(Colvée), in California by importedAphytis maculicornis(Masi) (Hymenoptera: Aphelinidae)

does not appear. First page follows. Introduction Olive scale, Parlatoria oleae (Colvée), was first discovered near Fresno, California, in 1934 and soon became an extremely serious pest. Chemical control methods against this scale were then inadequate and in the latter part of the 1940’s—at which time the currently used parathion treatments had not been developed—intensive efforts at biological control were initiated in California by the late H. S. Smith. In 1948 parasite material was received from Egypt, and from this the Egyptian Aphytis was obtained and apparently became established. In 1951 (Boyce (1952))5 searched the world distribution of the scale for its natural enemies and sent many shipments of material to R. L. Doutt, who initiated the biological control program in California. (Doutt’s (1954)) report of that early work indicated that the Persian Aphytis showed much promise; the report also noted the ineffectiveness or lack of establishment of several other introduced species. In appraising results of a parasite introduction, it is important to consider both the status of the host pest and the natural enemies which may be found attacking it prior to such introductions. Such pre-release knowledge is needed to properly evaluate the mortality factors already existing and to estimate the relative importance of subsequent introductions. Prerelease checks also assure investigators that an eventual introduction is not merely the establishment of a parasite species already present in the area. (Bacon (1941a)) reported studies on the action of Hemisarcoptes malus (Shimer) on P. oleae on olives and on several other host plants in the area