Knowledge of the approximate rate of nymphal development at different altitudes should be most useful in planning control operations against the clearwinged grasshopper, Carmnula Pellucida( Scudder), on rangelands in the interior of British Columbia. When hatching and development are observed ar any one altitude varying from under 1500 ft. to over 3500 ft., it should he possible on the basis of tGs knowledge to predict the most advantageous time to commence control operations at other altitudes on the same rangeland. Economic damage can be controlled by a single treatment, applied before the nymphs have developed to the fourth instar.