
Thrips
Slender pale yellow to brown insects under 2 mm long. Hide deep inside developing peony buds and between the overlapping petals as flowers open. So small they look like moving dust specks. Worst on light-colored bloom forms (white, pale pink) where the scarring shows.
Silvery or papery scars on the outside of swelling buds. Buds that do open often unfurl with brown-edged petals or distorted petal shape. Heavy infestations cause buds to abort entirely or open as malformed blooms. The damage targets the entire reason most growers plant peony.
Blue sticky traps at bud-swell, every 2 weeks
Hang blue sticky traps (Trappify or Garsum, ~$10) at the height of developing buds two weeks before normal bloom time. Thrips key on blue. The traps catch flying adults before they enter the buds where sprays can't reach. Replace every 2 weeks through the bloom window.
Spinosad on developing buds, every 5 days
Mix spinosad (Captain Jack's Deadbug Brew or Monterey Garden Insect Spray, ~$12 to $15) per label rate.
Spray developing buds and the leaves and stems just below them at dusk, starting when buds are pea-sized.
Repeat every 5 days until petals begin to color, then stop. Spinosad is hard on bees once flowers open.
Cut spent blooms and clear all litter at season end
Thrips overwinter as pupae in soil and plant debris under the clump. Cut peony stems to the ground after frost and rake out every bit of leaf litter from around the crown. Bag it and dispose. Do not compost. A clean clump entry catches them before they emerge in spring.

