Thrips

📐 FIELD GUIDE ILLUSTRATION

Original illustration by PestControlBasics.com. Use the labeled features above to confirm your identification.

🔬

PestControlBasics Editorial Team

Reviewed by Derek Giordano · Updated 2026

🔍 Identification

Adults: 1-2mm; slender; fringed wings; yellow to dark brown depending on species. Damage: silver or white streaking on petals and leaves (the rasping feeding removes cells); dark fecal spots on petals; malformed or scarred fruit; flowers that fail to open normally. Found inside flower buds and folded leaves — protected from most spray treatments. Western flower thrips (Frankliniella occidentalis) is the primary species of concern.

🧬 Biology & Behavior

Western flower thrips transmit Tomato spotted wilt virus (TSWV) — one of the most economically devastating plant viruses in commercial horticulture. TSWV has a host range of 1,000+ plant species and causes billions in annual crop losses. Once transmitted, no treatment cures the virus. Thrips also transmit Impatiens necrotic spot virus (INSV) and Iris yellow spot virus. Resistance to insecticides in western flower thrips populations is widespread and a major management challenge.

⚠️ Damage & Health Risk

Petal and leaf scarring reducing ornamental value; flower distortion; fruit scarring; transmission of devastating plant viruses (TSWV, INSV); economic losses in commercial floriculture and vegetable production.

🔧 DIY Treatment

Blue or yellow sticky traps for monitoring. Spinosad spray — the most effective homeowner option for thrips. Insecticidal soap kills on contact but requires complete coverage inside flower buds. Neem oil. For resistant populations: spirotetramat or abamectin. Biological control: predatory mites (Neoseiulus cucumeris) for greenhouse and indoor settings.

👷 When to Call a Pro

Commercial floriculture: strict resistance management rotating between spinosad, abamectin, spirotetramat, and cyantraniliprole to manage western flower thrips resistance — consult University Extension for current resistance profiles in your region.

❓ FAQ

Why don't my thrips sprays work?

Western flower thrips have developed resistance to most pesticide classes in many commercial regions. Additionally, thrips hide inside flower buds and folded leaves where spray doesn't penetrate. The combination of resistance and physical protection makes thrips among the hardest garden pests to control chemically. Spinosad remains effective against most populations but resistance is increasing — rotate modes of action.

Can thrips transmit plant viruses to my vegetable garden?

Yes — western flower thrips are major TSWV vectors in tomato, pepper, and many other vegetables. If you see TSWV symptoms (bronzing, necrotic rings, wilting) on tomatoes with thrips present, remove infected plants immediately to reduce virus source for thrips. There is no cure for TSWV — only prevention through vector management and reflective mulch that disorients incoming thrips.

🐛 Thrips