Abstract.Eggs of a local population ofLocusta migratoriaL. (Orthoptera: Acrididae) collected near Hirosaki (40.5oN) entered diapause when incubated at temperatures between 20 and 35oC. For diapause development the optimum temperature was 10oC. The lower thermal threshold for post‐diapause development was 14.7oC. After chilling at 10oC for 20 days, the rate of hatching varied with incubation temperature, being 0, 61% and 81% at 20, 25 and 30oC, respectively. After chilling for 40 days or more, however, almost all eggs hatched at 20–30oC. Diapause with a reduced intensity seemed to be eliminated easily by a high temperature of 25 or 30oC.When eggs chilled at 10oC for 20 days were kept at 20oC for 7 days or more before incubation at 25oC, almost all eggs maintained diapause. Most eggs chilled at 10oC for three 10 day periods separated by 3 days of warming at 25oC failed to terminate diapause. Daily alternations of 10oC (18 h) and 25oC (6h) decreased the diapause‐terminating effect of chilling. These facts suggest that diapause intensity can be restored if eggs chilled insufficiently are exposed to a moderately high temperature. This reversible change in diapause intensity would play an important role in maintaining diapause before w