Abstract: The bacteria in fruit flies alimentary tract have been known in advantages in their biology of the insect hosts. Different biochemical, gram reaction and motility tests was performed to identify the mid-gut bacterial community of laboratory host reared pumpkin fly, Bactrocera tau (Walker) (Diptera:Tephritidae). Colony characterization of the isolated bacteria was conducted on nutrient agar and MacConey agar plates. Isolated gut-bacterial species viz., Proteus rettgeri and Klebsiella oxytoca was examined by incorporated with protein (casein:yeast extract:sugar, 1:1:2) and sugar diet to study the effect of bacteria supplemented diets on the ovariole number and egg production of B. tau. Eight genera and nine bacterial species were identified under the family Enterobacteriaceae. The identified bacterial genera were Proteus, Klebsiella, Streptobacillus, Alcaligenes, Haemophilus, Erwinia, Chromobacterium and Flavobacterium. The mean ovariole number per ovary was recorded as 20.66±2.51, 20.56±3.53 and 22.41±3.75 for B. tau fed on P. rettgeri, K. oxytoca incorporated protein diets and only protein diet, respectively. Experimental result revealed no significant influence of gut bacteria added adult diets on egg/female/day of B. tau fed on above mentioned diet treatments.