Larvae of Bactrocera dorsalis Hendel (Diptera: Tephritidae), the oriental fruit fly, were reared in a liquid diet without mill feed (a biological bulking agent) on a large scale for the first time. Sponge cloth was used as an inert diet-supporting material. Experiments were conducted to identify the rearing components for factory-scale liquid diet rearing based on the larval duration, pupal recovery, pupal weight, adult emergence, flight ability, mating, egg hatch, sex ratio, egg production, and egging duration. The up-to-date recommended rearing conditions using liquid diet are as follows: formula: basic liquid diet includes sugar (8.99%), yeast (15.06%), nipagen (0.15%), sodium benzoate (0.15%), wheat germ oil (0.15%), citric acid (1.70%), and water (73.81%); tray: lid of pupation fiberglass box; seeding egg density: 2.5 ml; diet volume: 1,250 ml; screen: coarse screen or optional depending on the tray design; water quality: tap water; and additives: 0.15% wheat germ oil or higher. Fruit fly performance from larvae reared in this liquid diet is identical to that from conventional mill feed diet, and preliminary tests show that liquid diet technology can be used at the factory scale.