Laboratory tests were conducted to investigate the ability of the peach fly Bactrocera zonata (Saunders) to tolerate the lack of some food components (water - sugar - protein). These tests performed in three groups. 1- Continuous feeding (from emergence till death). 2- Feeding for the first 24 hours after emergence. 3- Feeding for the second 24 hours after emergence. Each group composed of the following treatments: sugar only feeding, protein only feeding, water only feeding,  sugar and water feeding, sugar and protein feeding,  water and protein feeding, sugar solution (10%) feeding and protein solution (5% buminal) feeding .in addition to two control treatments, Complete starvation and complete meal composed of water, sugar and protein. Results revealed that for the three feeding groups, sugar was the most significant component in the diet and its absence led to obvious reduction of fly life span. Presence of sugar, either alone or in combination with water or protein or even as a 10 % solution, compared to the sugar – free treatments, followed by water comes in the second rank (either alone or in combination with sugar or protein), and protein (either alone or in combination with water or sugar or in the form of 5 % solution) is the least significance.