Abstract
The seasonal sequence of parasitism of Unaspis yanonensis (KUWANA) was investigated in Kagoshima and Fukuoka prefectures in 1970-72. In Kagoshima during the first generation of the scale the parasitism by the dominant parasite, Aspidiotiphagus citrinus (CRAW), was very low but it gradually increased through the second generation and reached the maximum level of parasitism during the third generation of its host. However, parasitism by A. citrinus was again very low in the first generation of the host the following year. Such discontinuity was due to poor adaptability of this indigenous parasite to the invader. A.citrinus could not successfully overwinter in this scale, i.e., the immature parasites died within the over-wintering host during the months of January to March. But it may be able to do so in other diaspine scales such as Aonidiella aurantii (MASKELL), Aonidiella taxus LEONARDI and Quadraspidiotus perniciosus (COMSTOCK). The first generation of U. yanonensis was in the susceptible stage at a time between the first and second appearance of A. citrinus. Thus, the parasite scarcely had a chance to attack the scale. In Fukuoka the parasitism was very low throughout the year because the host scale had only two generations a year.
