In this study 4 treatments were applied on worker honeybees to study their stimulative effect on their ovaries deveIOpment. Five groups of newly emerged Carniolan worker bees were used for this study. The first and second bee groups were exposed to low temperature at 4 °C for V2 and 1 houre, respectively, while the third and fourth groups were expopsed to 40 "C for 24 hour and Co: for 5 minutes, respectively. The remaining group was used as a control. The bees were put in small cages supplied with a piece of wax comb containing pollen and supplied with diluted sugar solution and water. After applying the treatments the cages were put in an incubator at 34 °C . After 30 days the cages were inspected and the remaining workers were dissected to detrmine the degree of ovaries development in the different treatments. The effect of 72- and 1-hour cold treatments were superior to CO; treatment. The CO; had no stimulative effect on ovary development. The results suggested further using of lower temperature or incresing the exposure duration for the current low temperature as a tool for obtaining drones from workers with specific characters.