Successful rearing of alternative preys for the predatory bugs on synthetic diets facilitate the mass production of such predators. In this study, the saprophytic mite, Tyrophagus putriscentiae was reared on a simple semi-synthetic diet, as prey, that enabled rearing of the predatory anthocorid bug, Xylocoris galactinus under laboratory conditions of 25.5 ⁰C and 65% R.H. Egg incubation period, nymphal durations of both predator male and female, and preadult survival rates were estimated as well as dimensions of the five nymphal instars were measured. Further, measurements and longevity of both adult male and female were determined. Female fecundity and daily female reproductive were estimated.Survival rate of the nymphal stage of predatory bug was 90.24% with the lowest rate (74.8%) was recorded for first instar. The nymphal stage duration took 16±1.76 days for males and 21±1.05 for females. The female fecundity was 46.74±7.43 eggs with longevity averaged 25.91±4.79 days. Male longevity averaged 25.91±2.11 days. As each nymphal instar moulted, its dimensions increased. Males were longer (2.907 mm), however it were slimmer (0.727mm) than females (2.538mm). Successful development ofX. galactinus on T. putriscentiae with high nymphal survival rates is acceptable. Such easy rearing of T. putriscentiae on the semi-synthetic diet as a new alternative prey is in favor of the mass rearing not only of X. galactinus, but also for other anthocorid predators that used for biocontrol of phytophagous pests in greenhouses.