Tobacco caterpillar (Spodoptera)
A swarm-feeding, night-active defoliator that skeletonises leaves as a group when young and scatters to strip the crop when older.
- Pest type
- Defoliating caterpillar
- Attacks
- Leaves (many crops)
- Worst in
- Warm, humid kharif season
- Main risk
- Rapid night defoliation
Overview
The tobacco caterpillar (Spodoptera litura) is a highly polyphagous defoliator that attacks soybean, groundnut, cole crops, tomato, castor, cotton and many vegetables. The moth lays eggs in masses covered with brown hairs on the leaf underside, so the young caterpillars hatch and feed together in a group.
Young larvae scrape the leaf as a cluster, skeletonising patches and leaving papery membrane; as they grow they scatter across the crop, and the large larvae become night-feeders — hiding in the soil or leaf litter by day and emerging at dusk to defoliate, which is why the damage seems to appear overnight. A heavy outbreak can strip a soybean or groundnut crop quickly, so catching the grouped young stage is the key.
How to identify it
- Egg masses covered with brownish hair-scales on the underside of leaves — the earliest and easiest thing to spot and destroy.
- Patches of skeletonised leaf with papery membrane where grouped young larvae have grazed together.
- Larger caterpillars, smooth with dark markings (often a row of dark triangles along the back), scattered across the crop and hiding in the soil by day.
- Damage that seems to appear overnight, because the big larvae feed at dusk and after dark.
The damage it does
- Skeletonised and defoliated leaves that can strip a crop rapidly in a heavy outbreak.
- Feeding on pods, buds and fruit in some crops as leaves run out.
- Fast, patchy build-up from egg masses, so an untreated focus spreads quickly across the field.
- A polyphagous host range that lets it move between crops and carry over.
When to act
- Scout for egg masses and the first skeletonised patches — destroying grouped young larvae then is far easier than chasing scattered night-feeders later.
- Use pheromone traps to monitor moth flights and time action against young larvae.
- Act on threshold; the large night-feeding larvae are hard to reach, so early action pays.
Organic & cultural control
- Handpick and destroy egg masses and the grouped young larvae from the "skeletonised" leaves — highly effective early on.
- Spray SlNPV (the Spodoptera litura nuclear polyhedrosis virus) or Bt against young larvae, and use neem (NSKE 5%) as a deterrent.
- Set pheromone traps for mass-trapping and monitoring, and use poison-bait (bran + jaggery + a registered insecticide) at dusk to catch the night-feeding larvae.
- Deep-plough after harvest to expose pupae, keep bunds weed-free, and grow a castor trap crop to concentrate egg-laying where practical.
Chemical control
- Target young larvae before they scatter and turn night-active — CIB&RC-registered options include emamectin benzoate 5% SG, chlorantraniliprole, flubendiamide, spinetoram and indoxacarb, rotated by group.
- For large larvae, an evening application or a poison bait works better because they feed at night and hide by day.
- Rotate modes of action to avoid resistance and observe the pre-harvest interval, especially on leafy vegetables.
- Confirm the current recommendation and dose for your crop and zone 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
Whole patches of my soybean/groundnut leaves are skeletonised. What is it?
That grouped skeletonising of leaves is the young stage of the tobacco caterpillar (Spodoptera). The larvae hatch together from a hairy egg mass and feed as a cluster before scattering. Find and destroy the egg masses and grouped young larvae now — it is far easier than fighting the large night-feeding larvae later.
The damage appears overnight and I can’t find the caterpillars by day. Why?
Because the large tobacco caterpillars are night-feeders — they hide in the soil and leaf litter during the day and come out at dusk to feed, so the defoliation seems to appear overnight. Treat in the evening, or use a dusk-applied poison bait, and target the young larvae earlier when they are still exposed on the leaves.
What is the best early control?
Destroying the egg masses and grouped young larvae by hand, plus spraying SlNPV or Bt on young larvae, backed by pheromone traps. This hits the pest while it is concentrated and exposed. Reserve a rotated registered insecticide (evening application) and poison bait for larger, scattered, night-feeding larvae.
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.