Rice Weevils

Facts, Identification, and Control

Latin Name

Sitophilus oryzae

Appearance

Adult rice weevils measure approximately 4 mm in length and are reddish brown in color. Their wings feature faint yellow or red patterns. Deep, irregular pits are found behind the heads of these weevils, and their snouts can grow as long as 1 mm. Rice weevils are troublesome pests in warm, agricultural habitats such as the southern United States.

Behavior, Diet & Habits

Although rice weevils are not known to cause direct harm to humans, their destructive feeding habits can lead to grain loss. Contrary to their name, rice weevils feed on a variety of grains, including barley, wheat, corn, oats, rye and sorghum. They may even infest processed cereal goods such as macaroni.

Reproduction

Each female rice weevil is capable of laying four eggs a day and can produce up to 300 eggs in her lifetime. Females perforate kernels or seeds in order to lay single eggs inside. After doing so, the affected grain is sealed with gelatinous secretions. Larvae consume the kernel from the inside out, leaving behind an emptied husk.

In colder temperatures, the development cycle of the rice weevil may span more than 32 days. However, on average, larvae emerge within three days and develop into pupae within 18. Six days afterwards, adults emerge from the husk. Adults may live as long as six months.

Signs of a Rice Weevil

Infested items often will contain adult weevils as well as dead adults.  Grains will have exit holes from the emergence of the adult beetles.

Boll Weevils

Flour Weevils

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Wheat Weevils

Black Vine Weevils

Rose Weevils

White Pine Weevils