Thrips
Slender dark insects 1 to 2 mm long that walk along surfaces rather than fly. Hide in the folds of the white spathe and at the base of the yellow spadix. Tap an open spathe over a sheet of white paper to flush them out.
Brown streaks and silver scars across the white spathe, often with tiny black droppings alongside. Spathes emerge distorted or fail to open cleanly. New leaves come out scarred too. The bloom is the entire reason people grow calla lily, and thrips ruin it.
Blue sticky traps near the bloom canopy
Hang blue sticky cards (Trappify or Stikem, ~$10 per pack) at the height of the spathes. Thrips are drawn to blue and stick on contact. Replace every 2 weeks. Won't clear an infestation alone but knocks down the breeding population while spray works.
Spinosad spray, weekly for 3 weeks
Spinosad (Captain Jack's or Monterey Garden Insect Spray, ~$12 to $15) is the most effective home treatment for thrips. Spray every leaf surface and into the spathe folds at lights-out. Repeat weekly for 3 weeks to break the life cycle. Safe to use right up until the spathe opens.
Cut and bag affected blooms
Damaged spathes won't recover, and they're the breeding hotspot. Snip the stalk at soil level, seal the spent bloom in a plastic bag, and trash it. The rhizome will push fresh stalks once thrips pressure drops.
