Rice Moth
Corcyra cephalonica (Stainton)
📖 Description
Rice Moth (Corcyra cephalonica) is one of the most serious lepidopteran pests of stored rice and other stored food products across the Indian subcontinent and worldwide. Particularly severe in the major rice-producing and storage belts of India (Andhra Pradesh, Telangana, Tamil Nadu, Karnataka, Kerala, West Bengal, Odisha, Chhattisgarh, Punjab, Haryana, Uttar Pradesh, Bihar — India is the world’s second largest producer of rice, with over 130 million tonnes produced annually, and stored rice is a critical food security reserve). India is also a major exporter of rice (over 20 million tonnes annually, with exports worth over ₹1 lakh crore per year — making stored rice pest management a critical trade issue). The pest is unusual among stored grain pests because (a) it is the most common lepidopteran pest of stored rice in India — populations build up rapidly in stored rice, allowing severe infestations within weeks of storage, (b) the larva characteristically spins silken webs among the grains, binding them into ‘webbed clusters’ (distinct from other stored grain moths like the Indian Meal Moth which spins webbing only on the surface), (c) the larva prefers to feed on the germ (embryo) end of the grain — causing loss of germination (critical for seed rice) and loss of baking/malting quality (critical for food rice), (d) the pest has a short life cycle (30-40 days at 25-30°C) allowing 6-8 overlapping generations per year in stored grain — a single female lays 100-200 eggs, allowing exponential population buildup, (e) the larva contaminates the grain with silk, frass, exuviae and webbing — reducing market value and consumer acceptance, and (f) the larva’s metabolic water increases grain moisture — leading to fungal growth and mycotoxin production (Aspergillus flavus produces aflatoxins which are carcinogenic and regulated in international trade). IPM with clean dry grain storage (most critical preventive measure), hermetic storage bags (PICS bags — most effective preventive technology for small farmers), diatomaceous earth and Bt as preventive treatments, Corcyra pheromone traps for monitoring and mass trapping, need-based fumigation with Aluminium Phosphide (most effective curative treatment — must be used by trained applicators due to toxicity), stock rotation, and storage sanitation provides effective and sustainable control. The pest is a particular concern for Indian rice growers and traders because (i) rice is the staple food for over 60% of Indians — any loss of stored rice directly impacts food security, (ii) the crop is stored by millions of small and marginal farmers in household-level storages where pest management is difficult, (iii) India is a major rice exporter — any pest infestation reduces export quality and value, (iv) the Food Corporation of India (FCI) maintains massive grain reserves (over 50 million tonnes) where any infestation is a national food security issue, and (v) the pest’s rapid population buildup means a small initial infestation can become severe within months.
⚠️ Symptoms to watch for
- Webbing of stored rice grains with silk (characteristic 'webbed clusters' — distinct from other stored grain moths)
- feeding damage on the germ (embryo) end of the grain (causes loss of germination, loss of baking/malting quality)
- contamination of stored grain with larval frass
- silk
- exuviae and webbing (reduces market value and consumer acceptance)
- development of 'off-odours' in the grain (due to larval metabolic byproducts and secondary fungal growth)
- increased grain moisture (due to larval metabolic water) leading to fungal growth and mycotoxin production (Aspergillus, Penicillium)
- weight loss 5-15% in stored rice within 6 months of uncontrolled infestation
- complete loss of seed germination in heavily infested lots
🩹 Treatment
- Inspect stored grain weekly for webbing (early detection critical)
- maintain grain moisture below 12% (dry grain is unfavourable for moth development)
- fumigate infested grain with Aluminium Phosphide (Phostoxin) @ 1 tablet (3 g) per tonne of grain or per 1.5 m³ of stack space (highly effective — penetrates grain mass)
- apply Bacillus thuringiensis (Bt) @ 200 g/tonne of grain (effective against young larvae)
- install pheromone traps (Corcyra lure) @ 4/ha (or per 1,000 m² of storage) for mass trapping adult moths
- use hermetic storage bags (PICS bags — triple-layer hermetic bags) to suffocate larvae and adults
🌿 Organic treatments
- Apply Bacillus thuringiensis (Bt) @ 200 g/tonne of grain (effective against young larvae — disrupts larval gut)
- apply diatomaceous earth (DE) @ 1 kg/tonne of grain (abrades insect cuticle — causes desiccation, safe for human consumption)
- install Corcyra pheromone traps @ 4/1
- 000 m² for mass trapping adult moths (highly effective — captures male moths, reduces mating)
- use hermetic storage bags (PICS bags — triple-layer hermetic bags that suffocate larvae and adults by depleting oxygen)
- apply neem oil @ 5 ml/kg of grain (azadirachtin disrupts larval development)
- apply neem leaf powder @ 2 g/kg of grain (traditional Indian method — repels ovipositing moths)
- apply ground dried chilli powder @ 2 g/kg of grain (repels ovipositing moths)
- apply kaolin clay @ 1 kg/tonne of grain (coats grain — deters oviposition)
- apply entomopathogenic fungus Beauveria bassiana @ 200 g/tonne of grain
- install light traps @ 1/1
- 000 m² to catch adult moths
- expose infested grain to sun on hot dry days (larvae and adults die at grain temperature >45°C)
- use modified atmosphere storage (CO2 or N2 fumigation — oxygen <1% kills all stages within 7-14 days)
- freeze infested grain at -10°C for 7 days (kills all stages — practical only for small quantities)
🧪 Chemical treatments
- Aluminium Phosphide (Phostoxin) @ 1 tablet (3 g) per tonne of grain or per 1.5 m³ of stack space (fumigant — highly effective, penetrates entire grain mass, expose for 5-7 days under gas-proof cover — observe 24-hour aeration before handling)
- Malathion 5% DP @ 250 g/100 m² of storage surface (surface treatment — repels ovipositing moths)
- Deltamethrin 2.5% WP @ 20 g/L water as a surface spray (kills crawling larvae and adults)
- Spinosad 240 SC @ 1 ml/L water as a grain treatment (effective against larvae — low mammalian toxicity)
- Pirimiphos-methyl 50 EC @ 10 ml/L water as a surface spray (effective against all stages — relatively low mammalian toxicity)
- Cypermethrin 10 EC @ 2 ml/L water as a surface spray (effective against crawling stages) — always apply with appropriate PPE
- observe withholding period before grain is used for human consumption
- rotate fumigants and insecticides to slow resistance development
🛡️ Prevention
- Store only clean
- dry
- winnowed grain (grain moisture below 12% — dry grain is unfavourable for moth development)
- inspect incoming grain for infestation before storing (reject infested lots)
- clean and disinfect empty storage bins/bags before filling (cracks and crevices harbour larvae and pupae)
- seal cracks and crevices in storage structures (prevents moth entry and hiding)
- use hermetic storage bags (PICS bags — triple-layer hermetic bags that prevent moth entry and suffocate any insects already in the grain)
- apply diatomaceous earth (DE) @ 1 kg/tonne of grain as a preventive treatment (safe, long-lasting)
- apply Bacillus thuringiensis (Bt) @ 200 g/tonne of grain as a preventive treatment
- install Corcyra pheromone traps @ 4/1
- 000 m² for early detection and mass trapping
- install insect-proof screens on storage ventilators (mesh size <1 mm)
- maintain storage temperature below 25°C if possible (slows moth development)
- practice First-In-First-Out (FIFO) stock rotation (do not store grain for more than 6-12 months)
- do not mix old infested grain with new grain
- inspect stored grain weekly for webbing and adult moths (early detection critical — small infestations are easy to control, large infestations require fumigation)
- avoid spillage and dust accumulation in storage (these are ideal breeding sites)
- control moths in surrounding vegetation (alternate hosts)
- apply preventive insecticide treatment to empty storage structures before filling
🪴 Affected plants
- Stored Rice (primary host)
- Stored Wheat
- Stored Maize
- Stored Sorghum
- Stored Millets
- Stored Pulses
- Stored Oilseeds
- Stored Nuts
- Dried Fruits
- Chocolate
- Cocoa Beans
- Other Stored Food Products
🦋 Natural predators
- Trichogramma evanescens (egg parasitoid — limited efficacy in stored grain)
- Bracon hebetor (larval parasitoid — limited efficacy)
- Habrobracon spp. (larval parasitoid — limited efficacy)
- predatory bugs (Xylocoris — limited efficacy)
- predatory mites (Cheyletus — limited efficacy)
- entomopathogenic fungus Beauveria bassiana (limited efficacy in dry stored grain)
🌱 Host plants
- Oryza sativa (stored rice — primary host)
- Triticum aestivum (stored wheat)
- Zea mays (stored maize)
- Sorghum bicolor (stored sorghum)
- Pennisetum glaucum (stored pearl millet)
- pulses
- oilseeds
- nuts
- dried fruits
- chocolate
- cocoa beans
🔄 Lifecycle
- Adult moth emerges from pupa among the grains.
- Female lays 100-200 eggs singly or in small groups on the grain surface.
- Egg incubation 4-7 days.
- Larva passes through 5-7 instars over 18-25 days — spinning silken webs among the grains and feeding within.
- Larva pupates in a silken cocoon among the grains.
- Pupal period 7-10 days.
- Adult lifespan 7-15 days; female may lay 100-200 eggs in her lifetime.
- Total life cycle 30-40 days at 25-30°C; 6-8 overlapping generations per year in stored grain.
- Population peaks during warm humid conditions (Apr-Oct in tropical India).
📅 Season
- Active year-round in stored grain; peaks Apr-Oct (warm humid conditions most favourable for moth development — corresponds to the pre-monsoon and monsoon period when grain moisture tends to rise)
🔎 Appearance
- Adult is a small, slender, pale buff to greyish-brown moth (family Pyralidae — snout moth); forewings pale buff with two dark wavy transverse lines and dark spots at the apex; hindwings pale greyish-white with dark fringe; at rest the moth holds its wings tent-like over the body; labial palpi project forward like a snout.
- Larva is a small, cylindrical, dirty white to pinkish-cream caterpillar with a brown head; body sparsely covered with short setae; legs reduced.
- The larva characteristically spins silken webs among stored rice grains, binding grains together with silk and frass into characteristic 'webbed clusters'.
- Pupa is small, brown, in a silken cocoon among the grains.
💥 Damage level
- Moderate
🔁 Reproduction rate
- Fast
🗺️ Geographic regions
- Indian Subcontinent
- South Asia
- Southeast Asia
- Cosmopolitan in Tropical
- Subtropical
- and Temperate Stored Grain Worldwide
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