STUDIES ON THE SPATIAL DISTRIBUTION PATTERNS OF PINE CATERPILLAR (Dendrolimus pumctatus Walker)AND SAMPLING METHODS

The spatial distribution patterns of overwintering larvae of the pine caterpillar were studied by means of index of aggregation regression modle and frequency distribution. The result showed an aggregation distribution pattern for the larvae. Under low population density the distribution of the larvae obeyed Neyman distribution. In a single pine tree the larvae exhibited negative binomial distribution. The larval density between verticillate branches varied greatly and it should be divided into three groups. Different sampling methods were compared and the Z-shaped method found to be the best. The number of trees form which we took samples for survey was 24.