Experiments were conducted in the laboratory to assess the ability and stability of garlic (Allium sativum Linn.) aqueous extract to control the two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), and the carmine spider mite, Tetranychus cinnabarinus (Boisduval) in Egypt. Natural plant extracts, as (Allium sativum Linn.), have minimum-risk to the environment, so they can considered as an easy alternative to pesticides. Seven concentrations ranging from 2000 to 40000 ppm garlic were used to measure extract toxicity. Data showed that the maximum mortality values were 83.33and 86.67 % after 7 days, for T. urticae, and T. cinnabarinus, respectively. The effect of storage periods on the efficacy of different six concentrations of aqueous garlic extract on the same mite species was studied. Results indicated that the extract acaricidal activity decreased throw time for all tested concentrations. After four weeks it lost about 30% of its activity. Garlic aqueous extract significantly reduced egg deposition and egg hatchability of T. urticae and T. cinnabarinus. Regarding mites' mortality and fecundity, there were no statistically significant differences between the two species. These experiments demonstrated that garlic aqueous extract is effective in the control of both tetranychid mite pests.