Abstract: 【Aim】 This study aims to examine the embryonic development of overwintering eggs of Calliptamus italicus (L.) 【Methods】 We examined the embryonic development progress of diapausing eggs collected from the field and reared in the laboratory in 2013 and 2014. 【Results】 C. italicus eggs went through 18 stages during the embryonic development, including three blastokinesis movement, i.e., anatrepsis, revolution, and catatrepsis. Diapause mostly occurred at the 12th stage. The overwintering eggs resumed partly developing as early as on January 21st in the field, resulting in the longest developmental time, and their number decreased with prolonged overwintering-time of diapausing eggs until all the eggs terminated the diapause on March 29th. Eggs entered overwintering diapause at the 12th stage (diapause-incident stage) when they were laid at early-to-middle embryonic stages (from July 27th to August 16th and terminated the diapause on April 6th next year when the 5-day ground temperature was 2.67-15.95℃, with the average of 7.59℃. But eggs entered diapause at the 10th stage (November 4th, the 5-day temperature was 5.18-9.00℃, with the average of 7.32℃) when they were laid later (from August 28th to September 4th), and resumed development on March 29th (the 5-day ground temperature of 0.14-10.27℃, with the average of 3.78℃). 【Conclusion】 The time of C. italicus eggs entering and terminating diapause varies depending on the time when they are oviposited.

Key words: Calliptamus italicus, egg, embryonic development, diapause, diapause termination