Thrips
Tiny slender insects under 2 mm long, pale yellow to brown. Hide inside the 5-petal single flowers and along the central vein on the underside of lance-shaped leaves. Adults fly when disturbed. Often invisible until you tap a bloom over a white sheet of paper.
Brown streaks on petals, malformed buds that open lopsided, and a silvery sheen on leaves with tiny black dots of frass. The bigger threat is virus. Thrips vector tomato spotted wilt and impatiens necrotic spot virus, which cause ringspots, leaf curl, and stunted plants.
Blue sticky traps and spinosad rotation, every 7 days for 3 weeks
Hang blue sticky traps (Trappify or Stingmon, ~$10) just above the canopy. Blue catches more thrips than yellow.
Spray spinosad (Captain Jack's Deadbug Brew or Monterey Garden Insect Spray, ~$12 to $15) on flower buds, petals, and the underside of leaves at dusk.
Repeat every 7 days for 3 weeks. Spinosad reaches thrips inside buds where contact sprays miss them.
Pinch off any plant with virus ringspots
If you see concentric ringspots, leaf curl, or sudden stunting that doesn't match the watering pattern, the plant likely has tomato spotted wilt or impatiens necrotic spot virus. There's no cure. Bag and discard the whole plant to keep thrips from spreading the virus to neighboring containers and bedding plants. Do not compost.
Insecticidal soap on flower buds at lights-out
Spray ready-to-use insecticidal soap (Safer or Bonide, ~$10) directly into open flowers and on the underside of new leaves at dusk. Soap only kills on contact, so saturate the bloom interior where adults shelter. Repeat every 4 days for two weeks.
