Damage to apple crops infested with San Jose scale, Quadraspidiotus perniciosus (Comst.)

Abstract

The damage caused to apple fruit by San José scale, Quadraspidiotus perniciosus (Comst.), consists of red blotches and pitting. In Auckland, study of 5 apple varieties showed no variation in varietal susceptibility to the scale. The life history of San José scale in relation to the development of the fruit is described. Three generations may be present on a single fruit, The second generation is the most damaging. Initially, most red marks are caused by first in star nymphs. Of the total number of scales observed producing red marks on fruit, 62 per cent were sexed forms; and of these 65 per cent were male scales.