Taro Leaf Roller
Hedylepta indicata
📖 Description
The taro leaf roller, Hedylepta indicata (formerly Lamprosema indicata in older Indian literature), is the major lepidopteran defoliator of taro (Colocasia esculenta) cultivation in India. Adult moths emerge at dusk, mate, and females lay 150–300 eggs in clusters of 5–15 on the undersides of young taro leaves. The pale green larvae hatch in 3–5 days and immediately begin to web the leaf edges together with silk, forming a characteristic ‘folded’ or ‘rolled’ shelter within which they feed on the leaf tissue, leaving only the cuticle. The roll protects the larva from predators and from contact insecticides, making control particularly challenging. A single larva can destroy 3–5 leaves during its 15–22-day larval stage, and a heavily infested taro plant can show 50–90% of its young leaves rolled, browned, and unproductive. The pest is most damaging during the southwest monsoon (June–September), when taro is in its active vegetative phase and conditions are ideal for larval development. The rolled leaves are conspicuous and easy to spot, but growers often overlook early infestations — by the time 30–50% of leaves are rolled, the larval population is established and difficult to control. The pest is found across all major taro growing regions of India, with annual losses estimated at ₹60–90 crore. The leafy-vegetable trade in taro leaves (popular in eastern India, particularly in Bengal, Odisha, and Assam) is particularly affected — rolled, silk-webbed leaves are unsaleable as a leafy vegetable. Integrated management combines Btk sprays, NPV application, Trichogramma egg parasitoid releases, hand-collection of rolled leaves, and judicious use of reduced-risk insecticides. In the major taro growing states of Kerala (Palakkad, Malappuram), Tamil Nadu (Erode, Dharmapuri), Andhra Pradesh (East Godavari), Odisha (Cuttack, Puri), West Bengal (Midnapore, 24 Parganas), and Assam (Karbi Anglong), the leaf roller is one of the top 3 insect pests of taro, alongside the taro root aphid and the taro hornworm.
⚠️ Symptoms to watch for
- Larvae web the edges of young taro leaves together with silk, forming a characteristic 'folded' or 'rolled' shelter within which they feed on the leaf tissue.
- The rolled leaves dry up, turn brown, and the petiole may also be damaged.
- Heavy infestations can roll 50–90% of the young leaves on a taro plant, severely reducing photosynthesis and corm yield.
- Even lightly infested leaves show characteristic 'skeleton' feeding patches and silk webbing — these leaves have reduced market value for the leafy-vegetable trade.
- A single larva can destroy 3–5 leaves during its 15–22-day larval stage.
🩹 Treatment
- Manually collect and destroy rolled leaves — effective in smallholder taro plantings where the rolled leaves are conspicuous.
- Apply Bacillus thuringiensis kurstaki (Btk) at 1 g/L — bacterial endotoxin specifically targets lepidopteran larvae
- safe for taro leaves and corms.
- Spray neem oil (1% azadirachtin) at 5 ml/L with sticker — disrupts larval moulting.
- Install light traps at 1 per acre — adults are strongly attracted to UV light.
- Apply emamectin benzoate 5 SG at 0.3 g/L for established outbreaks (7-day pre-harvest interval).
🌿 Organic treatments
- Bacillus thuringiensis kurstaki (Btk) — 1 g/L with 0.5 ml/L non-ionic sticker
- spray at dusk on the undersides of leaves
- 2 sprays at 7-day intervals.
- Neem oil (1% azadirachtin) at 5 ml/L — larval growth disruptor and oviposition repellent.
- NPV (Nuclear Polyhedrosis Virus) of Hedylepta spp. — 250 LE/ha
- highly specific viral pathogen.
- Trichogramma chilonis egg parasitoid — 50,000 per ha, released at 7-day intervals.
- Hand-collection of rolled leaves — most effective in small-scale plantings.
- Light traps at 1 per acre — attracts ovipositing females.
🧪 Chemical treatments
- Emamectin benzoate 5 SG — 0.3 g/L
- chloride channel activator, 7-day PHI.
- Chlorantraniliprole 18.5 SC (Coragen) — 0.3 ml/L
- ryanodine receptor modulator, 7-day PHI.
- Indoxacarb 14.5 SC — 0.5 ml/L
- sodium channel blocker, 7-day PHI.
- Spinosad 45 SC — 0.3 ml/L
- spinosyns from Saccharopolyspora spinosa, 3-day PHI.
- Lambda-cyhalothrin 5 EC — 0.5 ml/L
- broad-spectrum pyrethroid, 7-day PHI.
- No chlorpyrifos, no monocrotophos — banned or restricted on taro.
🛡️ Prevention
- Inspect plantings weekly during the vegetative phase (June–September) — early detection of first-instar larvae is critical.
- Hand-pick rolled leaves whenever seen.
- Install light traps at 1 per acre from May onward.
- Maintain weed-free perimeter — wild Araceae are reservoir hosts.
- Apply neem cake (500 g per plant per year) as basal manure.
- Plant trap crops of cassava or sweet potato around the perimeter — these are preferred oviposition hosts but the larvae are easier to monitor and control.
- Prune and burn all rolled leaves during the southwest monsoon peak (June–September) — this breaks the cycle before the tuber-bulking phase.
🪴 Affected plants
- Taro (Colocasia esculenta) — primary economic host.
- Also recorded on elephant ear (Alocasia macrorrhizos), giant taro (Alocasia), tannia (Xanthosoma sagittifolium), and wild Araceae.
- All commercial Indian taro cultivars are susceptible, including 'Sree Rashmi', 'Sree Pallavi', 'Muktakeshi' (Orissa), and 'Thiruvananthapuram Local'.
🦋 Natural predators
- Trichogramma chilonis egg parasitoid — commercially available.
- Bracon hebetor braconid wasp — larval parasitoid.
- Cotesia flavipes braconid wasp — gregarious larval parasitoid.
- Tachinid flies (Ceromyia spp.) — larval parasitoids.
- Green lacewing Chrysoperla zastrowi — generalist predator.
- Spined soldier bug Podisus maculiventris — predator of late-instar larvae inside the roll.
- NPV — natural epizootic pathogen.
🌱 Host plants
- Taro (Colocasia esculenta) — primary host.
- Also elephant ear (Alocasia macrorrhizos), giant taro (Alocasia), tannia (Xanthosoma sagittifolium), and wild Araceae.
🔄 Lifecycle
- Egg → Larva (5 instars) → Pupa → Adult.
- Females lay 150–300 eggs in clusters of 5–15 on the undersides of young taro leaves.
- Eggs hatch in 3–5 days.
- Larvae web leaves and feed for 15–22 days, moulting 5 times.
- Pupation occurs inside the rolled leaf, lasting 7–10 days.
- Adults emerge at dusk, mate within 24 hours, and females begin oviposition 2–3 days later.
- Adult lifespan 7–14 days.
- Total cycle 28–40 days at 25–28 °C; 6–8 overlapping generations per year.
📅 Season
- Year-round in tropical taro growing regions, but outbreaks peak during the southwest monsoon (June–September) when taro is in its active vegetative phase and conditions are ideal for larval development.
- Lowest incidence in the cool dry winter (December–February).
🔎 Appearance
- Adult moths have a 20–25 mm wingspan, with straw-yellow wings marked by dark brown wavy transverse lines and a characteristic 'rolled-leaf' resting posture.
- The body is slender, 10–12 mm long.
- At rest, the wings are held tent-like over the body.
- Larvae are pale green semi-loopers with shiny black head capsules, reaching 18–22 mm when fully grown.
- Pupae are dark brown, 10–12 mm long, found inside the rolled leaf.
- Eggs are flattened, pale yellow, laid in clusters of 5–15 on the undersides of young taro leaves.
💥 Damage level
- Severe
🔁 Reproduction rate
- Fast
🗺️ Geographic regions
- Indian Subcontinent, South Asia, Southeast Asia, East Asia, Africa.
- In India: Kerala (Palakkad, Malappuram), Tamil Nadu (Erode, Dharmapuri, Coimbatore), Andhra Pradesh (East Godavari, West Godavari), Odisha (Cuttack, Puri, Balasore), West Bengal (Midnapore, 24 Parganas), Assam (Karbi Anglong, Cachar), Jharkhand, Chhattisgarh.
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