A preliminary exposure of more than 28 days to 15°±1℃ and short day length could induce final instar nymyhs of P. fuliginosa to tolerate a chilling temperature of 5.5°±0.5℃ for 90 days. The nymphs seem to enhance their resistance to cold without entering "true diapause". Second instar nymphs reared at 15°±1℃ seem to be more resistant to cold than those reared at 20°±1℃.
