How Weevils Become an Issue in Grains

Lifecycle and Infestation

• Egg-Laying: Female weevils lay eggs inside individual grains by boring into them and sealing the hole with a waxy secretion.
• Development Inside Grain: The larvae develop inside the grain, feeding on it from within, which destroys the grain’s structure.
• Emergence: Mature weevils emerge from the grain, leaving visible holes and debris behind.

Conditions Favoring Infestation

• Temperature and Humidity: Warm and humid conditions promote weevil reproduction and activity.
• Poor Storage Practices: Unsealed or improperly cleaned storage areas provide easy access for weevils.
• Presence of Contaminated Grain: Infested grains can introduce weevils to previously uninfested stock.

Types of Weevils in Grains

• Granary Weevil: Found in wheat, oats, and barley.
• Rice Weevil: Common in rice and other grains.
• Maize Weevil: Targets maize and other cereals.

Impact on Grain

• Weight Loss: Feeding by larvae and adults reduces usable grain weight and volume.
• Quality Degradation: Infested grains become discolored, musty-smelling, and contaminated with frass.
• Economic Losses: Infested grains often fail quality checks, leading to rejection or requiring costly treatments.

Prevention and Management

• Inspection and Cleaning: Regularly inspect grain and clean storage facilities thoroughly.
• Proper Storage: Use airtight containers or silos and control humidity and temperature.
• Treatment:
  • Use fumigants or insecticides approved for grain storage.
  • Employ natural methods like freezing or diatomaceous earth.
• Rotation and Hygiene: Avoid storing old and new grains together and clean out residues from previous storage.