Abstract
The seasonal fluctuation of pheromone trap catches indicated the fact that the oriental fruit moth repeats five generations a year in Okayama Prefecture. But twig injuries by fifth generation larvae were negligible in the peach field. The observational development zero and total effective temperature were calculated as 11.1°C and 383.7 degree-days from the number of days and average temperature interval between peak of emergences by the pheromone trap records. The second and subsequent emergence peaks coincided with that forecast time by the observational degree-days and accumulative effective temperatures. The result obtained in various districts indicated that the peak of primary generation was correlated with the temperatures during September through March and also with the annual average temperatures. The second and subsequent peak generation times at the seasonal prevalence in various districts coincided with that estimated time by the observational degree-days. The number of generations assessed with pheromon traps coincided with that estimated by dividing the cumulative effective temperature from April to September by the observational total effective temperature; a high correlation with the annual average temperatures was also demonstrated.
