In order to understand the occurrence and the developmental regularity of seabuckthorn carpenterworm (Holcocerus hippophaecolus) and predict its population density, the developmental threshold temperature (C) and effective accumulative tem- perature (K) of the carpenterworm pupae and eggs were analyzed under the conditions of constant and variable temperatures. The results show that the values of C and K of the carpenterworm pupae are (12.1 ± 0.2) °C and (295.2 ± 4.1) day-degrees at constant temperatures, and (15.5 ± 0.4) °C and (202.4 ± 13.1) day-degrees at variable temperatures. However, the values of C and K of the eggs at variable temperatures are (16.7 ± 0.8) °C and (101.5 ± 12.6) day-degrees. The differences of developmental threshold and effective accumulative temperature under the conditions of constant and variable temperatures of the carpenterworm pupae accord with the developmental regularity of most insects in nature. By comparing five different constant temperatures, the conclusion is that the optimum developmental temperature of the pupae is 21 °C when both the pupation of the mature larvae and the eclosion of the pupae are very accordant. Moreover, the percentage of eclosion is over 90%. The average developmental durations of the carpenter- worm pupae and eggs are 31 and 16 d at variable temperatures. In order to understand the occurrence and the developmental regularity of seabuckthorn carpenterworm (Holcocerus hippophaecolus) and predict its population density, the developmental threshold temperature (C) and effective accumulation potion (K) of the carpenterworm pupae and eggs were analyzed under the conditions The results show that the values ​​of C and K of the carpenterworm pupae are (12.1 ± 0.2) ° C and (295.2 ± 4.1) day-degrees at constant temperatures, and (15.5 ± 0.4) ° C and (202.4 ± 13.1) day-degrees at variable temperatures. However, the values ​​of C and K of the eggs at variable temperatures are (16.7 ± 0.8) ° C and (101.5 ± 12.6) day-degrees. The differences of developmental threshold and effective accumulative temperature under the conditions of constant and variable temperatures of the carpenterworm pupae accord with the developmental regularity of most insects in nature. By comparing five different constant temperatur es, the conclusion is that the optimum developmental temperature of the pupae is 21 ° C when both the pupation of the mature larvae and the eclosion of the pupae are particularly accordant. Moreover, the percentage of eclosion is over 90%. The average developmental durations of the carpenter-worm pupae and eggs are 31 and 16 d at variable temperatures.