Exposure of diapausing second-instar larvae of Choristoneura fumiferana to continuous light at 21 degrees C, after only 6 weeks' storage at 0 degrees C, induces emergence of larvae that will not emerge in photoperiods of 15 or 18 hours. Following the normal storage period (20 weeks) there is no such effect. Complete dark or 12-hour photoperiods inhibit emergence after storage periods of all lengths.