Clove Pink Borer
Chlumetia transversa
Borers, Mining & Weevils Insects Moderate Risk 20–25 mm wingspan (adult); 15–20 mm (mature larva)
📖 Description
Chlumetia transversa is a noctuid moth whose larvae bore into the tender shoots of clove trees, causing wilting and death of the affected terminals. India produces approximately 2,000 tonnes of clove annually from ≈5,000 ha, almost entirely in the Karnataka (Udupi, Dakshina Kannada) and Kerala (Kozhikode, Malappuram) coastal belt. The species is the most important shoot pest of clove in India, with infestation rates of 20–35 % commonly reported in young plantations. Multivoltine, with continuous overlapping generations throughout the year, though peak activity occurs during the post-monsoon period (September–November) when new shoot flush is abundant.
⚠️ Symptoms to watch for
- Terminal shoots wilt suddenly and droop; boreholes (1–2 mm diameter) are visible at the base of wilted shoots; frass accumulates at the borehole entrance in a characteristic 'spaghetti' pattern; successive shoot death gives the tree a 'stag-headed' appearance; flower buds (the harvested clove) on infested shoots dry up and fall; severe infestation of young trees (3–6 years) can stunt growth for 1–2 seasons.
🩹 Treatment
- Prune and burn all wilted shoots 5 cm below the lowest borehole — do this weekly during the flight season (April–November). Spray lambda-cyhalothrin 5 EC at 0.5 ml/L or emamectin benzoate 5 SG at 0.3 g/L at 30-day intervals during peak flight. Install light traps at 1/ha during April–November to mass-trap adults.
🌿 Organic treatments
- Prune and burn infested shoots weekly. Spray neem oil (1 % Azadirachtin) at 5 ml/L plus sticker at 15-day intervals. Apply Bacillus thuringiensis var. kurstaki at 1 g/L against early-instar larvae before they bore into shoots. Release Trichogramma chilonis at 50,000/ha against eggs. Spray Beauveria bassiana at 5 g/L in humid weather.
🧪 Chemical treatments
- Lambda-cyhalothrin 5 EC (0.5 ml/L), emamectin benzoate 5 SG (0.3 g/L), or chlorantraniliprole 18.5 SC (0.3 ml/L). Apply as foliar spray at 30-day intervals during peak flight (April–November).
🛡️ Prevention
- Maintain proper shade (30–40 % canopy) — fully exposed plantations suffer more. Avoid excessive nitrogen fertilisation which produces soft succulent shoots. Plant windbreaks of silver oak (Grevillea robusta) which also provide moderate shade. Prune lower branches to improve air circulation and reduce oviposition sites.
🪴 Affected plants
- Clove (Syzygium aromaticum) is the primary host; also recorded on nutmeg (Myristica fragrans) and occasionally on other Myrtaceae in mixed spice gardens of Kerala and Karnataka.
🦋 Natural predators
- Trichogramma chilonis (egg parasitoid, 25–35 % parasitism), Cotesia spp. (larval braconid parasitoid), predatory bugs (Anthocoridae — Orius spp.), spiders (Salticidae), and birds (bulbuls, white-eyes) that feed on adults and exposed larvae.
🌱 Host plants
- Syzygium aromaticum (clove — primary host), Myristica fragrans (nutmeg — occasional), other Myrtaceae in mixed spice gardens.
🔄 Lifecycle
- Egg (4–6 days, laid singly on tender shoots) → Larva (18–25 days, 5 instars, internal borer) → Pupa (10–14 days, in soil or leaf litter) → Adult (10–15 days).
- Multivoltine — 5–6 overlapping generations per year.
📅 Season
- Active throughout the year in coastal spice gardens; peak activity September–November (post-monsoon new flush) and April–May (pre-monsoon flush).
- Lowest activity in heavy monsoon months (June–August).
🔎 Appearance
- Adult is a noctuid moth with pinkish-brown forewings marked with darker brown transverse lines and a small whitish spot near the centre; hindwings are pale grey with a darker border.
- At rest, wings are folded tent-like over the body.
- Larvae are cylindrical, smooth, greenish-cream with a darker dorsal stripe and a brown head capsule; mature larvae reach 20 mm.
💥 Damage level
- Moderate
🔁 Reproduction rate
- Fast
🗺️ Geographic regions
- Indian clove tract (Karnataka — Udupi
- Dakshina Kannada
- Uttara Kannada; Kerala — Kozhikode
- Malappuram
- Kollam). Also reported from Sri Lanka
- Malaysia
- Indonesia
- Madagascar
- and Tanzania (Zanzibar).
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