Abstract
Sequential data taken on frequency counts of the eggs of Papilio xuthus LINNÉ per tree in a citrus grove were analyzed by the *m-m method (IWAO, 1968) and the process generating the distribution was examined on the basis of field observations on the oviposition behavior of butterflies. The distribution was always contagious and characterised by the values of two parameters, α>0 and β>1 of the *m-m regression. The former value indicated the tendency of a gravid female to diposit a few eggs to a tree per her visit. The latter value reflected the heterogenous conditions among trees. The heterogeneity was partly caused by the variability in the quantity of new leaves from tree to tree. The higher the square value of c.v. in the number of new leaves per tree was, the larger the value of β in the spring sprouting stage became. In the summer and autumn sprouting stages, however, no correlation was observed between the two values. The presence of already-hardened leaves is suggested to uniform the tree conditions in these stages. Spatial distribution of the eggs of P. xuthus in a larger citrus grove is discussed in relation to the possible mechanisms inducing contagiousness.
