a1 University of California, Berkeley
Studies in 1961 and 1962 showed that several naturally occurring conditions suppress the pear psylla. Temperatures above 100°F. caused mortality of nymphal stages and reduced adult oviposition. Crystallization of honeydew was a mortality factor in a few instances, and seemed to be associated with high temperature and low humidity. Absence of new growth and poor condition of leaves caused a steady decline in pear psylla numbers in abandoned orchards. Anthocoris antevolens White was an effective predator in unsprayed orchards and significantly reduced pear psylla populations. A parasite, Trechnites insidiosus (Crawford) was encountered, but its significance as a mortality agent was not determined.
(Received February 28 1963)