The members of the families Rhodacaridae and Laelapidae are free-living mites, found mainly in litter and the first few centimeters of the soil surface, and sometimes near plant roots, where they feed on insect larvae, springtails, nematodes, and phytophagous mites. At present some members of these families have been considered for use in biological control programs of Rhizoglyphus mite species (Acari: Acaridae). The development and fecundity of Gaeolaelaps aculeifer (Canestrini) and Protogamasellopsis rhizoglyphusi Amin & Khanjani, feeding on the astigmatic mites Rhizoglyphus echinopus (Fumouze & Robin) (Acaridae) and Carpoglyphus lactis (L.) (Carpoglyphidae) were studied at 25 ± 1 °C, 60 ± 10%, and in the darkness. The results showed that both predatory mites can feed and thrive on the two preys. Each predator species had a similar duration of the immature phase on both preys, and the duration was slightly longer for G. aculeifer (11.1–12.1 days) than for P. rhizoglyphusi (9.1–9.2). The oviposition time and life span were also similar for both species on both prey (respectively 17.7–19.8 and 35.9–39.8). However, the mean daily oviposition per female G. acullifer increased from about 2.9 eggs on R. echinopus to about 4.0 eggs on C. lactis. Also, the mean daily oviposition per female P. rhizoglyphusi decreased from about 3.8 eggs on R. echinopus to about 3.6 eggs on C. lactis. The net reproductive rate (R₀) ranged between 29.9 and 36.3 ♀/♀, except for G. aculeifer on R. echinopus, only 19.0 ♀/♀. The values of intrinsic rate of increase (r_m) ranged from about 0.136 ♀/♀/day (G. aculeifer feeding on R. echinopus) to about 0.230 (P. rhizoglyphusi feeding on C. lactis). Stage duration increased in starved specimens, G. aculeifer and P. rhizoglyphus adult females survived without food for a mean of 18 and 16.5 days, respectively. The results showed that mass rearing of both predators can be performed using C. lactis as prey, and also, both predators are able to develop and reproduce on R. ehinopus, a serious pest species in different countries, as prey. These data provide significant information for the practical application of predatory soil mites in the management of agricultural pests.