Thrips tabaci Lindeman is one of the main insect pests of onion (Allium cepa L.) in Colombia and several other countries. Strategies for its control are currently based on the use of chemical products. In a recent survey, Gaeolaelaps aculeifer (Canestrini) and Parasitus bituberosus Karg, two soil-dwelling predatory mite species (Acari: Mesostigmata), were found associated with this crop at Boyacá department, Colombia. Given that T. tabaci spends its pre-pupal and pupal stages in the soil, this study was conducted to evaluate the predation and oviposition of G. aculeifer and P. bituberosus on these developmental stages under laboratory conditions. The predators consumed up to 6.8 ± 0.52 and 6.9 ± 0.45 T. tabaci pre-pupae/ pupae, respectively, when offered 6 –10 prey a day. The maximum oviposition rates were 4.4 ± 0.25 eggs/female/day for G. aculeifer and 6.9 ± 0.26 eggs/female/day for P. bituberosus, with a mean egg viability higher than 91% for both predators. These results suggest that the evaluated predators may affect the population of T. tabaci under field conditions, and that the conduction of complementary studies on those predators is warranted, envisioning their practical use for T. tabaci control in Colombia.