Scientific name: Sitophilus granarius Family: Curculionidae Order: Coleoptera Risk level: Very high Category: Beetle
? What is the granary weevil
Scientific name: Sitophilus granarius
Family: Curculionidae
Order: Coleoptera
Risk level: Very high
Category: Beetle
The granary weevil (Sitophilus granarius) cannot fly because its wings are nonfunctional, which limits its spread more than that of the rice weevil. However, it reproduces inside the wheat kernel itself, making detection very difficult without laboratory testing.
Life cycle of the granary weevil
It undergoes complete metamorphosis. Eggs are laid directly on food, and the larva is the damaging stage. A full generation takes 4–8 weeks. Multiple generations may breed in an infested warehouse.
Distribution of the granary weevil
It occurs in food warehouses worldwide and is common in the Gulf, Saudi Arabia and Egypt, especially in hot warehouses.
Damage and risks associated with the granary weevil
It causes extensive damage to wheat and barley: kernels may be hollow while appearing sound on the outside. It causes major weight loss and reduces flour quality.
Signs of a granary weevil infestation
Signs include adult insects around light sources; larvae and silken threads in food (moths); droppings and hollow grains caused by weevils and beetles; and small white eggs on food.
Where granary weevils are found
They occur in grain stored in silos and warehouses. In early stages, they hide inside the kernel itself.
Granary weevil control methods
Monitor with pheromone traps. Spray the warehouse with pyrethroids. Fumigate stored products with phosphine or methyl bromide. For physical control, lower the temperature below 10°C or raise it above 55°C. Rotate stock using FIFO.
Granary weevil control products
Pyrethroids for warehouses, phosphine (PH₃) for fumigation, deltamethrin for residual spraying and diatomaceous earth for grain.
Requirements for controlling granary weevils in food facilities
FSSC 22000 Version 7: stored-product pests are high priority. Pheromone traps with weekly documentation are mandatory. BRCGS: stored-product pests in a product constitute a major Non-Conformance.
A fact about the granary weevil
Granary weevil larvae inside a kernel can be detected only by cutting it open, using X-rays or sorting by density (floating in water)—techniques used in grain-quality laboratories.
Frequently asked questions about the granary weevil
Q: How do stored-product pests enter a facility?
A: Usually through incoming shipments. Carefully inspect samples from each shipment and quarantine new purchases.
Q: Is a low temperature enough to eliminate stored-product pests?
A: Yes. Temperatures below 10°C for two weeks stop reproduction and kill vulnerable stages. Temperatures below −18°C for three days kill all stages
