Tea Looper Caterpillar
Biston suppressaria
📖 Description
Tea Looper Caterpillar is a major defoliator of tea across the Indian subcontinent, particularly destructive in Assam, West Bengal (Darjeeling, Dooars), Tamil Nadu (Nilgiris) and Kerala (Munnar) tea belts. The pest prefers shaded, mature tea and outbreaks often follow monsoon rains. The looper gait (only two pairs of prolegs) is characteristic of the family Geometridae — the larva moves by bringing its posterior prolegs forward to meet its thoracic legs, creating a ‘looping’ motion. Heavy defoliation reduces plucking surface and yield for 2-3 flushes after attack. Beyond tea, the pest attacks coffee, casuarina windbreaks and several timber trees. IPM with Bt applications against early instars, light trapping of adults and hand-collection of gregarious larvae provides effective control. The pest is prone to outbreaks in monoculture tea with excessive shade and improper pruning — balanced shade management and proper pruning cycle are key preventive measures.
⚠️ Symptoms to watch for
- Window-pane feeding by young larvae on leaf undersides
- complete defoliation of tea bushes in severe outbreaks
- scalloped leaf margins from adult feeding
- reduced plucking efficiency
- yield loss 15-30% in subsequent flushes
- plant death in repeated severe defoliation
🩹 Treatment
- Handpick larvae from young tea
- install light traps @ 1/ha for adult monitoring
- spray Bacillus thuringiensis @ 1 g/L on young larvae
- apply NSKE 5% in early evening
- use need-based insecticide when 5 larvae per bush
🌿 Organic treatments
- Bacillus thuringiensis var. kurstaki @ 1-2 g/L
- NSKE 5%
- neem oil 5 ml/L
- spray Beauveria bassiana @ 5 g/L
- hand-collect larvae and destroy
- set up light traps at dusk to attract adults
- spray NPV if available @ 250 LE/ha
🧪 Chemical treatments
- Emamectin benzoate 5 SG @ 0.3 g/L
- Chlorantraniliprole 18.5 SC @ 0.3 ml/L
- Quinalphos 25 EC @ 1.5 ml/L
- Indoxacarb 14.5 SC @ 0.5 ml/L
- Novaluron 10 EC @ 1 ml/L — apply at dusk when larvae emerge to feed
🛡️ Prevention
- Maintain proper pruning to improve bush aeration
- avoid excess shade
- install light traps to monitor adult emergence
- deep plough around tea bushes to expose pupae
- remove alternate hosts (Casuarina, Schima) near tea
- plant resistant clones (UPASI-9, TRF-1)
🪴 Affected plants
- Tea
- Coffee
- Casuarina
- Dalbergia
- Tectona
- Mangifera
- Schima
- Other Tree Crops
🦋 Natural predators
- Spiders
- Robber Flies
- Predatory Bugs (Orius, Cantheconidea)
- Birds (drongo, myna)
- Trichogramma spp.
🌱 Host plants
- Camellia sinensis
- Coffea arabica
- Casuarina equisetifolia
- Dalbergia sissoo
- Tectona grandis
🔄 Lifecycle
- Female lays 200-400 eggs in cracks of bark or under leaves.
- Eggs hatch in 7-12 days.
- Larvae feed for 25-40 days through 5-6 instars.
- Pupation in soil or leaf litter, lasting 15-25 days.
- Adult lifespan 7-15 days.
- Total life cycle 50-80 days; 3-5 generations per year.
📅 Season
- Year-round in tea, peaks Jul-Sep (monsoon) and Mar-May
🔎 Appearance
- Larva is a slender looper (Geometrid) with greyish-brown body, darker dorsal line and a characteristic looping gait (only two pairs of prolegs).
- Adult moth is greyish-white with dark wavy lines across wings, providing camouflage against tree bark.
- Rests with wings flat against branches.
💥 Damage level
- Moderate
🔁 Reproduction rate
- Moderate
🗺️ Geographic regions
- Indian Subcontinent
- South Asia
- Southeast Asia
- East Asia
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