Simple SummaryTo improve the control of stored-grain pests and protect the environment, the use of natural enemies is attracting increasing attention.Cheyletus malaccensisandCheyletus eruditusare effective natural enemies of common stored-grain pests, such asLiposcelis bostrychophilaBadonnel. To evaluate the predation potential of these two types of predatory mites, this study was conducted by comparing the life histories of two predatory mites and the functional responses onLiposcelis bostrychophila. The results indicate that compared toC. eruditus,C. malaccensishad a shorter development time and longer adult survival time at 28 °C and 75% RH and showed higher predation ability againstLiposcelis bostrychophilaeggs. It has been proven from both its life history of artificial breeding and the predation ability thatC. malaccensishas much greater biocontrol potential thanC. eruditusagainst stored-grain pests.AbstractCheyletus malaccensisOudemans andCheyletus eruditus(Schrank) are predators of stored-grain pests in China. The psocidLiposcelis bostrychophilaBadonnel is prone to outbreaks in depots. To assess the potential of large-scale breeding withAcarus siroLinnaeus and the biological control potential ofC. malaccensisandC. eruditusagainstL. bostrychophila, we determined the development times of different stages at 16, 20, 24, and 28 °C and 75% relative humidity (RH) while feeding onA. siro,as well as the functional responses of both species’ protonymphs and females toL. bostrychophilaeggs at 28 °C and 75% RH.Cheyletus malaccensishad a shorter development time and longer adult survival time thanC. eruditusat 28 °C and 75% RH and could establish populations faster thanC. erudituswhile preying onA. siro. The protonymphs of both species showed a type II functional response, while the females showed a type III functional response.Cheyletus malaccensisshowed a higher predation ability thanC. eruditus, and the females of both species had a higher predation ability than the protonymphs. Based on the observed development times, adult survival times, and predation efficiency,Cheyletus malaccensishas much greater biocontrol potential thanC. eruditus.