We made an experiment on the thermal reaction in the nymphal stage of Eucorysses Grandis THUNBERG, in which the nymph were left in the 0℃ environment for 10 minutes and the temperature was raised at the rate of 1 ℃ per 5 minutes.
The results are summarized as follows.
1) Seven grades are given as the index of the activities, "Slight movement" 9.6～15.4℃, "Keep ing body in normal position "11.8～16.4℃, "Beginning of locomotion" 13.2～19.0℃, "Strong activity" 34.2～41.2℃, "Excilement" 37.0～43.6℃, "Falling down or keeping body in abnormal position" 41.4～47.2℃, "Heat stupor" 44.0～49.0℃.
2) The nymph in the older stage requires higher temperature than in the earlier stage to act.
3) Juding from these results it is supposed that the scope of the injurious activity of the nymph is in temperature from 14.69～17.02℃ mearly to 35.67～39.63℃, which is the limit of the activity.
4) Nymphsin all instars showed no difference in the breadth of temperature for doing normal activity or potential activity.