Abstract
The number of generations per year of the cabbage webworm, Hellula undalis FABRICIUS was investigated in Ano, Mie Prefecture, Central Japan. Seasonal changes in the number of larvae on Japanese radish plants and males caught by virgin female traps showed that the cabbage webworm occured six times in 1985. The number of generations in a field agreed with the value calculated from the total effective temperature for the development of one generation of the cabbage webworm and the monthly mean temperatures in 1985. Since the males were caught in April and May, it is assumed that the cabbage webworms hibernate in the larva and pupa stages. However, most of the larvae which were found on Japanese radish in autumn died in winter, and a small number of larvae were found until April of the following year.
