Mohamed, H.Z., S.M. Ali and H.M. Khodair. 2023. Efficiency of the Egg Parasitoid Trichogramma evanescens for the Control of Potato Tuber Moth, Phthorimaea operculella under Laboratory Conditions. Arab Journal of Plant Protection, 41(4): 391-397. https://doi.org/10.22268/AJPP-41.4.391397 The efficiency of the egg parasitoid Trichogramma evanescensin controlling the eggs of the potato tuber moth, Phthorimaea operculella, was evaluated at two temperatures 20 and 25ºC and using different ages of host eggs in the laboratory. The temperature of 25˚C was the best for the period required for blackening of the host's eggs, parasitism efficiency and adult’s emergence rate. The results also showed the use the 396 مجلة وقاية النبات العربية، مجلد ،41 عدد 4 ) 2023( host's eggs age of 24, 48 and 72 hours led to a parasitism rate of 83.33, 68.33 and 58.33%, respectively, at temperature of 25ºC. The results also showed the importance of the age of the host eggs age in determining the parasitoid emergence rate, which reached 75.9% when 24 hours old eggs were used. Results obtained indicated that the parasitoid Trichogramma evanescens can be used as a biological control agent of the potato tuber moth. Keywords: Trichogramma evanescens, Phthorimaea operculella, biological control