Thrips on roses

Thrips damage on roses is often misidentified or overlooked until flowers open to reveal petals covered in brown streaks and lesions. The insects themselves are tiny -- 1–2mm -- and spend most of their time deep inside developing buds where they are invisible and protected from most contact.

Thrips damage on roses is often misidentified or overlooked until flowers open to reveal petals covered in brown streaks and lesions. The insects themselves are tiny — 1–2mm — and spend most of their time deep inside developing buds where they are invisible and protected from most contact insecticides. By the time the bud opens and reveals the damage, the thrips have already fed, reproduced, and moved on.

I don't grow roses at my current Long Island garden. This guide draws on UC IPM, Penn State Extension, and Cornell Cooperative Extension research.

The pests

The western flower thrips (Frankliniella occidentalis) is the primary thrips pest of roses in North America. Per UC IPM, other thrips species can occasionally be found on roses, but F. occidentalis is the most economically significant and has the widest geographic range.

Per Penn State Extension, thrips are in the order Thysanoptera; they have fringed wings and highly specialized mouthparts that rasp plant tissue and suck up the exuded cellular content. They are not true sucking insects — they scrape and puncture tissue rather than inserting stylets.