Abstract
Surveys were carried out on 35 trees at the 18 year old japanese persimmon (Hiratanenasi) orchard, where the densities of the overwintered larvae of both species were considerably high. In early spring, both species lived upon the bud, but the distribution of each larvae on the bud, classified by its position on a twig, differed, namely in the case of P. kraunhiae its density on the top bud of a twig was significantly higher than on other buds at lower levels, and the case of P. pergandei it was approximately the same on all buds. Thus it may be said that the larvae of each species distributed independently on each bud, and the existence of another species on the same bud did not affect their behaviour in bud selection. In the orchard, the frequency distribution of the number of each larvae per tree seemed to agree with concentrated type. In each tree, the frequency distribution of the number of each larvae per bud varied with their density, namely when the density was low the type of distribution agreed with Poisson's curve but when the density was high (over about 0.5 per a bud) it deviated from Poisson's curve and fitted to the concentrated type. This trend was completely the same for both species.
