The purpose of this study is to determine the impact of different thermal stresses on univoltine Bombyx mori embryos and grown larva in the terms of larval haemolymph proteins , biological and economical characters. The experiment was designed to expose egg groups to different temperatures as follows; a group exposed to 0°C for one hour, a group exposed to 0°C for two hours, a group exposed to 40°C for one hour and a group exposed to 40°C for two hours, followed by 2 hours recovery at room temperature in addition to a control group, the same was applied to the grown larval groups. The larval haemolymph of tested groups were subjected to protein analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Data revealed that considerable alteration in temperature hamper the protein activities which affects the embryonic development and hatching of eggs. 40ºC for two hours was lethal dose for embryo. The highest measured parameters were recorded for eggs exposed to 40ºC for one hour. While for grown larvae, the highest results were recorded for larvae exposed to 0ºC for 1 hour. Thermal stresses induced protein changes with the appearance of new bands. The epigenetic degree of similarity recorded 50% between the control egg group and the egg groups exposed to 0ºC for 2 hrs and 40ºC for 1 hrs. as well as, for grown larva, between control larval group and larval group exposed to 40ºC for 2 hrs.