To investigate the cold adaptation of the orange wheat blossom midges,Sitodiplosis mosellana (Gehin),their round cocoons were collected and sampled from 5 different geographical districts,including Nanyang and Huixian of Henan Province,Xi’an of Shaanxi Province,Baoding of Hebei Province,and Tianjin. Results showed that the supercooling points of the round cocoons significantly decreased with the rise of the latitude. The average supercooling point was maximum in Huixian colony, which was -18.46 ℃, and minimum in Tianjin colony which was -25.34 ℃. There were large variations in Xi’an and Nanyang colony, which have the lower latitudes and lower supercooling points. Supercooling points of round cocoons had positive relationship with local extreme low average temperatures in January and February.