In vitro preliminary tests executed to evaluate the possibility of using microwave to disinfest fruits as a postharvest quarantine treatment using a cocking microwave oven. Subjecting the eggs, 1^st, 2^nd and 3^rd larval instars of both medfly and peach fruit fly for 10, 15, 25 and 30 seconds and estimate the mortality percentage. Results revealed that there were a gradual increase in mortality percentage for the larval instars for both flies, eggs and larval instars of peach fruit flies have a higher heat tolerance than medfly stage consequently, lower mortality percentage for the same time period microwave treatments. Also, revealed that eggs of fruit flies (medfly and peach fruit fly) have a higher resistance to heat than larval instars. Thus, Microwave can be a very efficient tool for disinfesting treatments of fruit flies since it can give a very fast rise in temperature in very short time which is a very important parameter in qualifying postharvest quarantine method to avoid fruit damage, still a challenges are presents for developing microwave processes to be applicable as a postharvest quarantine treatment.