Angoumois Grain Moth (Sitotroga cerealella): Identification, Damage & Control

 

The Angoumois Grain Moth (Sitotroga cerealella) is one of the most serious pests of stored grain worldwide. Unlike many other moths that infest flour, cereals, or processed products, this insect is a primary pest: it attacks whole kernels of wheat, corn, rice, barley, sorghum, and other cereals.

Named after the French region of Angoumois, where it was first described centuries ago, this moth has spread globally with the trade of grain. It thrives in both warm and temperate climates, making it a challenge for farmers, storage operators, and households alike.

The damage caused by Angoumois Grain Moths includes reduced grain weight, contamination, lower germination rates, and huge economic losses. This guide explores how to identify the pest, understand its biology, detect early infestations, and apply both household and professional control methods

Identification

Adults:

• Wingspan: 12–18 mm.

• Color: pale yellowish-brown to gray, with long narrow wings.

• Antennae: long, slender, threadlike.

• Behavior: weak fliers, active mostly at dusk and dawn.

Larvae:

• White to yellowish caterpillars, 5–7 mm long when mature.

• Head: brown.

• Feeding: inside kernels, hollowing them out.

Eggs:

• Small, white, laid on or near kernels.

• Hatch within days in warm conditions.

Pupae:

• Found inside the grain kernel, where larvae complete development.

Biology and Lifecycle

• Egg laying: Females lay 100–200 eggs directly on kernels or in crevices.

• Hatching: Eggs hatch within 4–7 days under favorable conditions.

• Larvae: Develop inside kernels for 2–3 weeks, feeding on the endosperm.

• Pupation: Occurs inside the kernel, lasting about 1 week.

• Adults: Live 1–2 weeks, long enough to reproduce.

Optimal conditions:

• Temperature: 27–32 °C (81–90 °F).

• Humidity: 70% or higher.

Generations per year:

• In warm climates: 4–6 generations.

• In tropical regions: up to 8 generations annually.

Ecology and Distribution

The Angoumois Grain Moth originated in the Mediterranean but is now found worldwide.

• Common in Europe, Asia, Africa, and the Americas.

• Prefers warm, humid storage conditions.

• Often spread through international grain trade.

Unlike pantry moths such as the Indian meal moth, the Angoumois Grain Moth infests whole kernels, making it dangerous not just for stored products but also for seed stock.

Risks and Damage

• Kernel destruction: Larvae hollow out grains from the inside.

• Weight loss: Infestations reduce grain volume and weight significantly.

• Quality reduction: Infested grain is downgraded or rejected in trade.

• Seed germination: Infested kernels lose viability, making them useless for planting.

• Contamination: Infested stock contains dead insects, frass, and silk.

• Economic losses: Estimated global losses run into billions annually.

In addition, infested kernels provide entry points for fungi, encouraging mold and mycotoxin production.

Signs of Infestation

• Small circular exit holes in kernels where adults emerged.

• Fine powder or frass around infested grain.

• Musty odors in infested storage.

• Reduced germination of seed stock.

• Live moths flying around storage bins, especially at dusk.

Because larvae live inside kernels, infestations often go unnoticed until adults appear.

Household Control

Though less common in homes, Angoumois Grain Moths can arrive in infested rice, corn, or wheat.

• Inspection: Check for holes, dust, or live moths near stored food.

• Removal: Discard infested products immediately.

• Freezing: Store small quantities at –18 °C for 1 week.

• Heating: Expose grains to 55–60 °C for several hours.

• Storage: Use airtight containers; avoid leaving grains in open bags.

Industrial and Professional Control

Large-scale management is essential in silos, warehouses, and ports.

Sanitation:

• Clean residues and old grain dust.

• Seal cracks and crevices.

Aeration and Cooling:

• Reduce grain temperature below 15 °C to halt reproduction.

Fumigation:

• Phosphine is the most common fumigant, effective against all life stages.

• Requires licensed professionals.

Modified Atmosphere Storage (MA):

• High CO₂ or low O₂ environments suffocate larvae inside kernels.

• Residue-free, increasingly popular for organic grain.

Biological Control:

• Research shows some parasitoid wasps can reduce moth populations.

• Not yet widely adopted in industrial practice.

Integrated Pest Management (IPM):

• Combine sanitation, monitoring, fumigation, and alternative methods.

• Use pheromone traps to detect adults early.

Case Study: Infestation in Stored Rice

A rice warehouse in India reported reduced seed germination rates. Inspection revealed Angoumois Grain Moth larvae inside kernels.

Actions taken:

• Quarantined infested stock.

• Fumigated bulk storage with phosphine.

• Introduced aeration cooling systems.

• Implemented pheromone monitoring to catch early infestations.

The combination of fumigation and IPM restored seed quality and reduced future risks.

FAQ

Q: How are Angoumois Grain Moths different from pantry moths?
A: Pantry moths infest flour and processed foods, while Angoumois Grain Moths attack whole kernels.

Q: Do they fly?
A: Yes, though weak fliers, they can spread between storage sites.

Q: Can infested kernels still be planted?
A: No, larvae destroy the seed’s germ, making it non-viable.

Q: What is the best control method?
A: For bulk grain, fumigation and modified atmosphere storage are most effective.

Q: Do they bite humans?
A: No, they only damage grain.

Final Thoughts

The Angoumois Grain Moth is more than just a nuisance—it's a pest that silently undermines food security around the globe. Its life cycle inside kernels makes infestations difficult to detect until the damage is already done. By the time adults emerge, seed quality is lost, weight is reduced, and entire shipments may be compromised.

For households, the battle is straightforward: inspect products, freeze or heat-treat small amounts, and use airtight storage. But for farms, mills, and warehouses, the challenge is far more complex. The pest not only affects food quality but also threatens seed viability, which directly impacts crop production for the following season.

What makes this insect especially challenging is its adaptability. Even with sanitation and careful handling, moths often find their way back through the global grain trade. That’s why professional strategies like fumigation, aeration cooling, and modified atmosphere storage are essential.

If there’s one lesson to take away, it’s this: the Angoumois Grain Moth thrives when it goes unnoticed. Vigilance, monitoring, and swift action are the real tools to protect grain, whether in a small household pantry or in a thousand-ton storage facility.

Read more in our blog and explore guides on many other enemies. Stay informed.

Disclaimer

This article is for informational purposes only. Pest control laws and approved chemicals vary by country. For best results and legal safety, we strongly recommend contacting a licensed pest control professional in your local area. Always make sure that the pest control technician is properly certified or licensed, depending on your country’s regulations. It’s important to confirm that they only use approved products and apply them exactly as instructed on the product label. In most places in Europe, UK, or USA, following label directions is not just best practice—it’s the law.

Author

Nasos Iliopoulos
MSc Agronomist & Certified Pest Control Expert
Scientific Director, Advance Services (Athens, Greece)
Licensed Pest Control Business – Ministry of Rural Development & Food (GR)

References

• Britannica – Angoumois Grain Moth

• Wikipedia – Angoumois Grain Moth

• Penn State Extension – Angoumois Grain Moth