Metarhizium for thrips
Both US LALGUARD M52 labels list thrips, the granules specifically for thrips pupae in soil and potting media, where the fungus persists longest. Direct field data on western flower thrips were not in the sources we checked; in greenhouse cages, three sprays of strain F52 cut a related pest, chilli thrips, on pepper by 84–93%. It kills slowly, in 3–7 days, and the label says it kills more slowly when it is very cold or hot, so use it preventively alongside predatory mites rather than as a rescue.
Before you order
Spores of an insect-killing soil fungus, sold as granules to mix into potting media and soil, or as a liquid to drench or spray. Labelled for thrips pupae and vine weevil larvae in soil, and for whiteflies, mites and aphids on leaves. It is not labelled for wireworms in the US. How it works, how to tell it has established and the supplier list are on the full Metarhizium brunneum strain F52 profile.
Other controls for western flower thrips
- Amblyseius cucumerisPredatory mite · 50–100 /m² per release (Koppert); UC IPM: 10–50 mites per plant, weekly; or sachets
- Orius insidiosusPredatory bug · 1–2 /m² per release; up to 10 /m² in hot spots
- Orius laevigatusPredatory bug · 0.5–1 /m² preventive once the crop flowers; 5–10 /m² in and around hot spots
- Amblyseius swirskiiPredatory mite · 25 /m² preventive, 50 at first detection, 100–300 on hot spots (Cornell); sachets repeated after four weeks
- Stratiolaelaps scimitusPredatory mite · 100–500 /m² of compost surface per release (Koppert); once at planting (UConn) or repeated once or twice (Koppert)
- Beauveria bassiana strain GHAMicrobial insecticide (fungus) · Label rate — 1–2 qt per 100 gal (BotaniGard ES / Mycotrol ES) or 1–2 lb (22WP)