Rice leaf folder
Folds a rice leaf into a tube and scrapes it hollow from inside — the pale streaked leaves that matter most when they hit the flag leaf at grain filling.
- Pest type
- Leaf-folding caterpillar
- Attacks
- Leaf blades (esp. flag leaf)
- Worst in
- Lush, humid, high-N crops
- Main risk
- Folded flag leaves at grain fill
Overview
The rice leaf folder caterpillar folds a leaf blade lengthwise into a tube, fastening the edges with silk, and feeds inside by scraping away the green surface tissue. This leaves long, pale, papery, transparent streaks and gives the crop a scorched, whitish look from a distance.
Most of the season the crop tolerates some leaf folding without yield loss, and natural enemies keep it in check. It matters when folding is heavy on the upper leaves — especially the flag leaf — during the booting to grain-filling stage, because those leaves feed the grain. Lush, over-fertilised, closely-spaced crops with a humid canopy favour it, as with many rice pests.
How to identify it
- Leaves folded lengthwise into tubes, fastened with silk, with a caterpillar inside when you open one.
- Long pale, papery, transparent streaks where the green surface has been scraped away; the field looks whitish or scorched from a distance.
- Small caterpillars that wriggle backwards quickly when the fold is opened.
- Heaviest in dense, lush, over-fertilised patches with a closed humid canopy.
The damage it does
- Scraped, non-functional leaf area that reduces photosynthesis when folding is heavy.
- Real yield loss mainly when the upper leaves — especially the flag leaf — are folded during booting to grain filling.
- A scorched, whitish crop appearance, but often more alarming than damaging at the vegetative stage.
- Worse in over-fertilised, dense crops where natural enemies are also disrupted.
When to act
- Don’t panic over folding in the vegetative stage — the crop compensates and natural enemies usually keep it in check.
- Act when folding is heavy on the upper/flag leaves during booting to grain filling, on the recommended threshold (percentage of damaged leaves).
- Avoid early broad-spectrum sprays that kill natural enemies and can worsen leaf folder and other rice pests.
Organic & cultural control
- Avoid excess nitrogen and dense planting; an open canopy with recommended spacing is less favourable and easier for natural enemies to work in.
- Conserve spiders, parasitic wasps and other natural enemies, which normally keep leaf folder below damaging levels.
- Release Trichogramma where recommended, and run a rope/stick across the canopy to dislodge larvae in small fields.
- Grow recommended varieties and keep bunds free of grassy alternate hosts.
Chemical control
- Spray only when damage to the upper leaves crosses threshold at the critical booting–grain-filling stage — CIB&RC-registered options include chlorantraniliprole, flubendiamide and cartap hydrochloride for rice.
- Good coverage of the upper canopy is needed to reach caterpillars inside the folds; a rope passed ahead of the sprayer opens some folds.
- Rotate insecticide groups, avoid pyrethroids that trigger resurgence of other rice pests, and observe the pre-harvest interval.
- Confirm the current recommendation and dose for your 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 rice leaves are folded into tubes with white streaks. Should I spray immediately?
Not necessarily. Leaf folding in the vegetative stage often looks worse than it is — the crop compensates and natural enemies usually control it. Spraying matters mainly when folding is heavy on the upper and flag leaves during booting to grain filling, since those leaves feed the grain. Check the threshold before treating.
When does leaf folder actually cost yield?
When the upper leaves, especially the flag leaf, are heavily folded during the booting to grain-filling period. Those top leaves supply the grain, so losing their green area then reduces filling. Folding lower down, earlier in the season, is usually compensated for and rarely worth spraying.
Why avoid broad-spectrum sprays for leaf folder?
Because they kill the spiders and parasitic wasps that normally keep leaf folder — and brown planthopper — in check, which can trigger a worse pest outbreak. Manage nitrogen and spacing, conserve natural enemies, and reserve a selective registered insecticide for threshold-level damage on the upper leaves at the critical stage.
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.