Thrips

Thrips are tiny, slender insects with four fringed wings and measure roughly one-sixteenth inch long. You will notice silver or bleached streaking on petals and flowers, along with shiny tar-like spots where thrips excrete. Flowers may develop uneven petal colors or distorted shapes. On ornamental shrubs and roses in western Washington, damage becomes apparent in mid-summer.

Scout flower buds and open flowers regularly. Remove heavily infested buds and flowers to reduce adult populations. For roses and hibiscus, time insecticide sprays just before petal fall to protect developing fruit. Use insecticidal soap or spinosad targeting the pre-adult stages. Conserve native predatory mites and parasitic wasps by minimizing broad-spectrum pesticide use.