Thrips
Barely-visible rasping sap-suckers that silver the leaves, curl the growth and scar the fruit — and carry viruses in chilli, onion and groundnut.
- Pest type
- Rasping sap-sucker
- Attacks
- Young leaves, flowers, fruit
- Worst in
- Warm, dry weather
- Main risk
- Leaf curl / bud-necrosis virus
Overview
Thrips are tiny (1–2 mm), slender, fast-moving insects — pale yellow to brown — that hide in leaf folds, flower buds and leaf axils. They do not pierce like an aphid; they rasp the surface open and drink the sap that leaks out, which is why the damage looks like silvery scratching rather than clean holes.
In chilli the same species spreads the leaf-curl complex ("murda"), in onion it turns the leaves silvery-white and cuts bulb size, and in groundnut it transmits bud-necrosis virus. Thrips thrive in warm, dry weather and multiply extremely fast, so a light dry spell can turn a scattered population into a crop-wide problem within a couple of weeks.
How to identify it
- Very small, slender insects that scurry away when you open a curled leaf or a flower — tap a flower over white paper and watch the specks move.
- Silvery or white streaks and patches on leaves where the surface has been rasped, later turning brown and papery.
- Young leaves curl upward or crinkle, buds and flowers drop, and fruit (chilli, grape, mango) is scarred with corky silver-brown patches.
- Blue sticky traps catch thrips well and are the easiest way to confirm and monitor them.
The damage it does
- Silvering, curling and crinkling of young leaves; heavy infestation dries and distorts the whole growing point.
- Flower and bud drop, and scarred, russeted fruit that is downgraded at the market — a major loss in chilli, grapes and mango.
- In chilli, thrips drive the leaf-curl "murda" complex (with mites), cupping and shrivelling the leaves.
- Virus transmission — bud-necrosis in groundnut and tomato, and yellow/leaf-curl complexes elsewhere.
When to act
- Hang blue sticky traps and check curled leaves and flowers twice a week, especially through warm, dry spells when numbers spike.
- Act early in virus-prone crops (chilli, groundnut, onion) — thrips are hard to reach once leaves curl tightly around them.
- Watch the weather: a break in the rains during a susceptible stage is the classic trigger for a thrips flare-up.
Organic & cultural control
- Blue sticky traps mass-trap adults; spray neem oil / NSKE 5%, which repels thrips and disrupts their moulting.
- Spray Beauveria bassiana or Lecanicillium (Verticillium) lecanii — entomopathogenic fungi that work well on thrips in humid conditions.
- Keep the crop free of weed hosts, avoid excess nitrogen, and irrigate adequately — a water-stressed crop in dry heat is where thrips explode.
- Conserve predatory mites and minute pirate bugs by avoiding broad-spectrum sprays.
Chemical control
- Thrips resist insecticides quickly and hide deep in curled tissue, so rotate groups and get thorough coverage into the folds and flowers.
- CIB&RC-registered options include spinosad 45% SC, fipronil 5% SC, cyantraniliprole and spinetoram — choose one registered for your crop and rotate between groups.
- Add a good spray volume and wetting so the chemical reaches thrips sheltering inside curled leaves and buds; observe the pre-harvest interval.
- Confirm the current recommendation and dose for your crop and area with your local KVK.
Crops most at risk
Where this problem is called out in our crop guides — open a crop for the full package of practices.
Frequently asked questions
My leaves have silvery streaks and curl upward. What causes it?
That silvery scratching with upward-curling young leaves is classic thrips damage — they rasp the surface and drink the sap, and the emptied cells turn silver then brown. Open a curled leaf or tap a flower over white paper and you will see the tiny slender insects move. Blue sticky traps confirm them.
What is "murda" in chilli?
Murda (leaf curl) is a complex caused mainly by thrips together with mites: the leaves cup, curl and shrivel and the plant stops growing. Because thrips also carry viruses, the two effects compound. Managing thrips and mites early — traps, neem, entomopathogenic fungi and rotated insecticides — is how you keep murda in check.
Why do thrips suddenly explode in dry weather?
Thrips breed fastest in warm, dry conditions and a break in the rains removes the rain-splash that knocks them off the plant. That is why a dry spell during a susceptible stage is the classic trigger. Adequate irrigation, blue traps and early neem or fungal sprays blunt the flare-up.
Symptoms and control measures follow ICAR, KVK and state agricultural-university package-of-practices; any named chemical is a registered use. Always read the product label and confirm the dose for your crop and zone. editorial policy.