Thrips on Houseplants
Thrips are slender insects (1–2 mm) that rasp leaf surfaces and suck out the contents, leaving silvery streaks, deformed new growth, and black fecal specks. They breed quickly and are commonly introduced on new plants.
How to identify thrips
Adults are slender, 1–2 mm long, pale yellow to dark brown. Easier to spot than the thrips: silvery streaks on leaves, distorted new growth, and tiny black dots (frass) on leaves.
Damage to look for
Silvery or bronze streaks on upper leaf surfaces, distorted or curled new growth, tiny black specks of frass, leaf drop in severe cases.
Life cycle (why they spread so fast)
Egg to adult in ~15 days at room temperature. Eggs are laid inside leaf tissue (hard to remove). Pupation happens in soil, which makes integrated soil + foliar treatment important.
How to get rid of thrips
- Rinse the plant thoroughly to dislodge adults, then spray with insecticidal soap or spinosad-based spray every 5–7 days for 3–4 cycles.
- Drench the soil with a systemic insecticide (imidacloprid, per label, not on edibles) since pupae hide in the medium.
- Yellow or blue sticky cards trap winged adults and help monitor population.
- Isolate the plant for at least 4 weeks.
How to prevent thrips
- Inspect new plants (especially flowering ones, where thrips often hide) for 3–4 weeks before adding to a collection.
- Avoid bringing in cut flowers from outdoors during thrips season.
Per-species treatment guides
Treatment varies slightly by plant. Find your species below for a dedicated guide.
Source: UC IPM — Thrips