Neoseiulus cucumeris

Silvery streaks on the leaves with tiny black dots scattered through them, and new growth coming in scarred — that is thrips, and Neoseiulus cucumeris (still widely sold as Amblyseius cucumeris) is the thrips mite the commercial greenhouse world runs on. There is a reason for that: it is cheap, it is reliable, and it does the one job that matters most. This is the bottle — adults in a vermiculite carrier, released all at once, so the predator-to-prey ratio spikes the moment you open it.

It is also about as simple as pest control gets. Nothing to mix, nothing to spray, no residue on the leaves and no re-entry interval — you tip them onto the plant and leave them to it. They hunt the leaf undersides and the folded new growth where a spray never lands, they find the thrips without your help, and thrips cannot develop resistance to being eaten. Safe around people, pets and anything you plan to eat.

It also takes broad mites and cyclamen mites, and it is the species with the published record on broad mite. That matters more than it sounds: broad mite damage is routinely misdiagnosed as overwatering, calcium deficiency or virus, so if you have unexplained distorted new growth on an aroid, a pepper or a begonia, a bottle of cucumeris is a cheap thing to put on it while you work out what it is.

One thing to understand about the timeline. Cucumeris takes thrips at the first larval stage — the day or two after hatching — so you are killing the generation coming up behind the one you can see. A full treatment runs about 45 days as every thrips and every egg already in the plant cycles through that window. Judge it on new leaves emerging clean, not on adults disappearing. Adding Sf nematodes as a soil drench is the single biggest thing that shortens it, because it removes the pupal stage.

Best for: An active thrips problem you can see, and broad or cyclamen mites. Works at 65–80°F; below about 50% humidity the eggs can fail to hatch.
How many: Sizes go by plant count. Releasing more than strictly necessary has no downside — the excess disperses and declines naturally once the pest is suppressed.
Arrives as: A bottle of loose adults in a vermiculite carrier. Deploy the day it arrives; there is no holding option.
Speed: About 45 days for a full cycle.
Safe around: People, pets, plants and food crops.
Not for: Adult thrips — Orius insidiosus is the one that takes those. Not prevention; that is the sachet. Not the soil stage, where Sf nematodes reach the pupae. Nor Echinothrips: in the trial that tested it, cucumeris did not reduce the population, and Amblyseius swirskii is the mite with the better record there.