Identification
Rice weevils are small, reddish-brown to black beetles measuring about 2–3 mm in length. They have distinctive snout-like projections and small pits on their wing covers. Adults possess four faint yellowish spots on their elytra (wing covers) and are capable of flying. The larvae are white, legless, and develop entirely inside whole grains.
Lifecycle & Reproduction
Rice weevils undergo complete metamorphosis, including egg, larva, pupa, and adult stages. A single female can lay 300–400 eggs, depositing them individually inside whole grains. Larvae feed and develop inside the grain for 18–35 days before pupating. Pupation lasts 6–14 days, after which the adult emerges by boring through the grain. The entire lifecycle takes about 30–60 days, depending on temperature and humidity. Adults can live up to five months.
Habits, Diet & Behavior
Rice weevils primarily infest whole grains such as rice, wheat, corn, barley, and pasta. They prefer warm, humid environments and are active year-round. Adults can fly and are attracted to light, often gathering near windows when disturbed. Unlike many other pantry pests, rice weevils infest food while it is still in storage or processing rather than after packaging.
Where You’ll Find Them / Typical Locations
- Stored grains in pantries, warehouses, and granaries
- Food processing plants and grain storage facilities
- Grocery stores and bulk food bins
- Farms and agricultural storage silos
Threats & Danger
Rice weevils cause extensive damage to stored grains by feeding and laying eggs inside kernels. This leads to grain spoilage, weight loss, and reduced quality. Infestations can result in significant economic losses in agricultural and food processing industries. While they do not bite or spread disease, their presence in stored food makes it unfit for consumption.
Prevention
- Store grains and dry food in sealed, airtight containers.
- Regularly inspect stored food for small holes or damaged kernels.
- Keep storage areas dry and well-ventilated.
- Use bay leaves or cloves as natural deterrents.
- Rotate stock frequently, using older food first to prevent long-term storage.
Signs of Infestation
- Small, round holes in grains or rice kernels.
- Presence of live adult weevils crawling in or around food storage areas.
- Powdery grain dust accumulating at the bottom of storage containers.
- Increased presence of flying beetles near food storage.
How to Get Rid of It
- Discard infested grains: Dispose of contaminated food in sealed plastic bags.
- Freeze infested items: Placing grains in the freezer for at least a week will kill eggs and larvae.
- Thoroughly clean storage areas: Vacuum shelves and wipe down with vinegar or soapy water.
- Use pheromone traps: These can help monitor and control adult populations.
- Heat treatment: Drying grains at 120°F (49°C) for several hours can eliminate infestations.
- Professional pest control: For large-scale infestations, experts may use fumigation or chemical treatments.