Rice Weevil


Rice Weevil Control: Protect Your Home

Facts

Scientific Classification: Sitophilus oryzae (Linnaeus)

Class Order Family
Insecta Coleoptera Curculionidae

Description

As a destructive stored-product pest, the rice weevil can cause the complete devastation of grain kept in elevators and bins, as the grain typically remains undisturbed for great lengths of time. The insect reproduces and the larvae develops in the kernels of the grain itself.

Appearance

What Do They Look Like?

Size: Varying in size from 3/32 to 1/10 of an inch, rice weevils are typically long and slender in appearance.

Color: Adults are generally dull reddish-brown to black in color with a hard carapace or outer shell marked by four light red to yellow spots.

Characteristics: Characterized by a particularly long pronotum or snout, the rice weevil also features a pitted prothorax and an elytra with longitudinal grooves. Strong flyers, the insects are also attracted to light.

Geographic Range

First found in India, the rice weevil now has a cosmopolitan distribution throughout the United States and the rest of the world thanks to international commerce.

Food

What Do They Eat?

Considered one of the most devastating stored product pests found in the United States, rice weevils eat a variety of grains and other foods, including rye, barley, buckwheat, table beans, stored cotton, grapes, cashews, cereals and wheat products such as pasta and birdseed.

Biology

Female rice weevils deposit a single egg into the hollowed out cavity of a kernel of grain before sealing the opening. An adult rice weevil can lay as many as 400 eggs during a lifespan that typically lasts up to five months. The eggs hatch in about three days, producing creamy white larvae with black heads. Rice weevil larvae complete three molts before maturing into adults after finishing pupation within the kernel. New adults stay inside the grain until the body hardens.

Detection

  • Look in unsealed food containers, where the presence of warm grains near the surface may indicate a rice weevil problem.
  • May notice the flying insects hovering in or around a food source.
  • Holes in stored grains may also signal an infestation of rice weevils.

Problems Caused by Rice Weevils

Highly destructive, rice weevils create major headaches in grain elevators and other storage facilities that hold similar food items. The pests develop within the grain itself, leaving behind hollowed-out kernels that can no longer be used. In undisturbed environments with the right conditions, rice weevils can almost completely destroy entire elevators or bins of stored grain. Their ability to fly only exacerbates the problems they cause.

Signs of Infestation

In grain silos, elevators and other storage facilities, infested grains may feel heated near the surface. Additionally, the grains may be damp to the point that molds and fungi start to appear. Damaged kernels may also indicate a rice weevil infestation as does the sight of recently emerging adults. Rice weevils are excellent fliers, though they may fall to the ground and feign death when startled. Finding the pests near a source of light may also denote a possible infestation.

Prevention Tips

Keeping storage bins properly sanitized may be the best way to avoid rice weevils. Removing all old grain and dust before putting in new items can help cut down on potential incursions. Additionally, any spilled grains should be removed immediately. Treat and seal all cracks, crevices and other points of entry. Approved insecticides may be used but only when handled by a knowledgeable individual like a trained pest control professional.

To keep rice weevils out of the home, all grains, pastas and similar food products should be appropriately stored in insect-proof containers with tight lids. Rotate product with consistency using old food items before new ones to help reduce the risk of a rice weevil infestation.

Tips for Removal from Home

With large infestations, it remains prudent to contact a trained professional to help with the removal of the damaging stored-product pests. As rice weevils reproduce inside of grains, the cost of trying to eradicate an infestation without professional assistance may end up being as high as the cost of losing the stored product itself. Certified pest professionals have the knowledge and training to eliminate the problem and prevent the insects from returning and causing more damage in the future.