Khapra Beetle
Trogoderma granarium
📖 Description
Khapra Beetle is one of the most destructive stored grain pests across the Indian subcontinent and a quarantine pest in many countries. Both larvae and adults feed on stored grain, but larvae cause most damage. The pest is exceptionally difficult to eradicate because larvae can survive without food for up to 2 years by entering diapause, hide in cracks and crevices of storage structures, and are resistant to many insecticides. Heavy infestation can cause 50-70% grain weight loss within 6 months. The pest particularly thrives in warm, dry storage conditions typical of Indian grain stores. Strict quarantine, fumigation with aluminum phosphide, hermetic storage, and thorough sanitation of storage structures are essential for management. Khapra Beetle is listed as one of the world’s 100 worst invasive species.
⚠️ Symptoms to watch for
- Hollowed grain with only husk remaining, cast larval skins and frass in grain, live larvae crawling on grain surface, foul smell in heavily infested grain, weight loss up to 50-70% in 6 months, total grain loss in unmanaged storage
🩹 Treatment
- Fumigate stored grain with aluminum phosphide @ 1 tablet (3g) per tonne grain, heat infested grain to 60°C for 30 minutes, apply malathion 5% dust @ 250g/100kg grain, dispose of heavily infested grain by burning
🌿 Organic treatments
- Solar heat treatment — spread grain in thin layer under sun for 2-3 days, freeze grain at -5°C for 4 days, mix grain with diatomaceous earth @ 1 kg/tonne grain, apply neem oil @ 5 ml/kg grain, mix with crushed neem or karanj leaves @ 100 g/kg grain, use hermetic storage (PICS bags), apply Bacillus thuringiensis dust
🧪 Chemical treatments
- Fumigate with Aluminum phosphide @ 1 tablet (3g) per tonne grain in airtight storage (observe 7-day exposure + 2-day aeration), treat grain with Malathion 5% dust @ 250 g/100 kg grain, apply Dichlorvos 76 EC @ 0.5 ml/m3 as space treatment, treat storage structure with Deltamethrin 2.5 EC
🛡️ Prevention
- Store only well-dried grains (<10% moisture), clean and disinfect storage structures before loading, fumigate empty gunny bags and storage structures, use hermetic storage (PICS bags), inspect grains monthly, rotate stored stock (first in first out), quarantine imported grain, monitor with pheromone (female sex pheromone) traps @ 1/50 m2, prevent migration by sealing cracks in storage structures
🪴 Affected plants
- Stored Wheat, Rice, Maize, Sorghum, Pearl Millet, Pulses, Oilseeds, Spices, Dried Fruits, Stored Grain Products
🦋 Natural predators
- Predatory Mites, Anthocorid Bugs, Parasitic Wasps (Lariophagus), Earwigs
🌱 Host plants
- Stored Wheat, Stored Rice, Stored Maize, Stored Sorghum, Stored Pulses, Stored Oilseeds
🔄 Lifecycle
- Female lays 50-150 eggs loosely in grain or in cracks.
- Eggs hatch in 4-7 days.
- Larvae feed for 4-8 weeks (or up to 2 years in diapause), passing through 5-7 instars.
- Pupation occurs within the last larval skin, lasting 5-10 days.
- Adults live 5-15 days.
- Total life cycle 30-60 days under optimal conditions; up to 2-3 years in diapause.
- 4-5 generations per year in warm storage.
📅 Season
- Year-round in storage, peaks during warm dry months (Apr-Aug)
🔎 Appearance
- Small, oval, dark reddish-brown beetles covered with fine yellowish-brown hairs.
- Larvae are yellowish-brown, hairy, segmented grubs growing up to 6 mm, found crawling in stored grain and feed on grain surface.
💥 Damage level
- Severe
🔁 Reproduction rate
- Fast
🗺️ Geographic regions
- Indian Subcontinent
- Middle East
- Africa
- Worldwide Stored Grain
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