Thrips predator mites (Arnblyseiu's cucumeris) are effective thrip feeders under high humidity (70-85%) growing conditions, against all species of thrips. They also will eat an occasional spider-mite and other small pests. However, reports have been poor with lower humidity environments, so these are most useful for greenhouses and other locations with high humidity levels. But in some gardens thrips predator mites have been an excellent control.

Use 100-500 per plant, reapply as needed. Thrips parasites (Thripobius semileutius) are a good control for thrips that pupate in leaf tissue, as opposed to the soil (like most do). How can you tell? When you examine leaves closely, if you see little eruptions on the leaf itself (these are caused by the thrip hatching, and look like miniature "volcanoes", somewhat like a pimple with a crater in the middle, and are very obvious under magnification), then thrips parasites will be effective.

Otherwise, use another control. (It's normal for many thrips species to leave black fecal specks on leaves, along with a "silvery" film, but these look nothing like the "craters" that leaf-pupating thrips cause when hatching.