1968 年 3 巻 4 号 p. 163-175
From laboratory rearings at constant tempertures and the analysis of light-trap records, it was ascertained that the relation between temperautre and velocity of non-diapause development of Hyphantria cunea was linear between 14°C and 26°C. The calculated threshold of development was about 10°C for completing the whole immature period, but the values for egg and pupal stages were somewhat higher. The thermal constant was 750 to 850 day-degrees to complete non-diapause development. H. cunea is, however, considered to be practically unable to complete its life cycle at 12°C because of high mortality. Temperatures near 30°C are also unfavourable for the development. Short days that induce pupal diapause may have a little effect on the relation between temperatuers and larval development. It was sugested that hot summer in the middle part of Japan would be an unfavourable condition for the life of Hyphantria cunea.