Races of Apomictic Parasitic Hymenoptera Introduced into California1

Abstract

Aspidiotiphagus citrinus and Prospaltella perniciosi collected in China during 1948-49 were introduced into localities where they had been already established for several years. These late introductions, however, unlike the older introductions, successfully parasitized Aonidiella aurantii. This phenomenon of host-determined races of parasites should be recognized in importation programs.