On the type of larval appearance and seasonal development of the San José scale

Abstract

In southwest Japan, the San Jose scale, Quadraspidiotus pernicious (Comstock), has been abundant on satsuma orange during last several years. Observations on this scale on citrus trees in 1965-71 showed that the insect completed two generations during the growing period and overwintered as third-generation larvae, entering diapause in the latter stage of the first instar. Overwintering larvae continued slowly to develop throughout the cold season to the stage immediately proceeding the first molt and development was then suspended until the temperature reached a suitable level. Therefore, they all molted with a short period of about a week in February or March, though the overwintered larvae are of widely varying ages. Then, the females which hibernated in state of the mature first instar larvae produced the larvae of the 1st generation almost simultaneously with a sharp fluctuation curve at the end of May. The duration from hatching to oviposition was completed its development in the 1st generation in 45-51 days, in 2nd in 43-54 days and in 3rd in 209-272 days, respectively.