Rice Weevil Bite, Damage, Life Cycle, Control

| January 31, 2018

Learn all about rice weevil bite, damage, life cycle and control over these. As their name obviously suggests, they really enjoy rice, however, rice isn’t the only thing they enjoy. Rice weevils are known to eat dried beans, cotton, nuts, cereal, any wheat product, corn, flour, pasta, bread and other grain products found in most any home. Rice weevils are even known to go outside of the pantry to eat product not meant to be food like fabrics in clothing and furniture.

Rice weevils are usually found in grain storage facilities or processing plants, infesting wheat, oats, rye, barley, rice, and corn. Although not often found in the home, they are sometimes found infesting beans, birdseed, sunflower seeds, dried corn, and to a lesser degree macaroni and spaghetti. Rice weevils do not bite, nor do they damage wood or furniture.

There are many pantry pests which can infest homes and businesses. Though Meal Moths, Grain Beetles and Flour Beetles are very common, Rice Weevils are just as likely to be the unwanted insect in such areas. Rice Weevils are small and easy to kill, but they can complete their life cycle quickly

Rice weevils are a serious stored product pest, and if left unchecked, they have the ability to compromise food supplies on a massive scale. They are known to contaminate bird seed (specifically sunflower seeds), corn, wheat, rice, beans, nuts, cereals, stored cotton, along with grapes, apples, and pears. In southern states, adults may infest crops out in the fields and contaminate food processing facilities when the infested crops are brought in.

Control of these insects involves inspection and removal of infested food products, discarding the heavily infested material, repackaging material in new containers, and vacuuming kitchen cabinets. Products that need to be retained may be placed in the freezer for several weeks to kill adults and larvae.

Rice Weevil Bite, Damage, Life Cycle, Control

What is Rice weevil?

The rice weevil (Sitophilus oryzae) is a stored product pest which attacks several crops, including wheat, rice, and maize. Adult is small (2.5 to 4 mm), dark brown with 4 distinct reddish to reddish yellow patches on the elytra. The adult rice weevil can fly. The adult can live up to two years, with the female laying up to 400 eggs during her lifetime.

Rice weevil Bite

Rice weevils do not bite or hurt people, nor do they spread disease. They will not cause structural damage, but they will destroy any grains you have stored in your pantry. They are not harmful to humans or animals. Although it may seem unsavory to you, they can be eaten along with any food they have infested without causing any ill effects.

Rice weevil Damage

Rice weevils are very destructive grain pests. Of the three, the rice weevil is probably the most insidious, owing largely to the ability of flight. All three weevils develop as larvae within the grain kernels. They frequently cause almost complete destruction of grain in elevators or bins, where conditions are favorable and the grain is undisturbed for some length of time. Infested grain will usually be found heating at the surface, and it may be damp, sometimes to such an extent that sprouting occurs. Wheat, corn, macaroni, oats, barley, sorghum, Kaffir seed, and buckwheat are just some of the grains and products on which these weevils feed. If large numbers of rice weevils are present, they increase the temperature of the stock by breeding in the excrement. This may cause mold.

Rice weevil Life Cycle

Adults are 2-3 mm long dark brown weevils, with four faint yellow spots on the elytra. Body is punctured with minute pits. Sitophilus granarium is slightly larger in size and is found in more temperate climate. Adults do not fly but try to crawl away when disturbed. Their longevity can be up to 5 months. Eggs are whitish, oval, 0.7 mm long. Females chew a small depression on the surface of rice grain, lay an egg in it and seal it with a gelatinous fluid for protection. Grubs make their way into seed to feed on kernel. They are plump, 3-4 mm long, legless, dirty white in colour with a brownish head. Pupation takes place inside the grain. Pupa is light yellowish but later turns dark brown. Adult emerges by cutting a hole in the grain.

Rice weevil Control

Rice weevil control by seed treatments is reliant on either the adults, in the case of cypermethrin, or larvae, when triflumuron is used, feeding on the treated grain and hence the insecticide. When feeding on treated grain, insecticide is ingested and the insect is killed. Eggs and larvae feeding exclusively within the seed are not controlled by this method, as there is no intake of chemical. However, when they emerge, insecticide is ingested from the surface of the seed and control is achieved.

The use of insecticides is discouraged around food materials. Insecticides are supplementary to sanitation and proper storage. Household insecticides have no effect on insects within food packages. For extra protection, some treat seeds or grains before storage with dusts or sprays of synergized pyrethrins, labeled for this use. If the problem becomes severe and widespread, contact a reputable, licensed pest control operator who has the training, experience, equipment, and insecticides to get the control job accomplished safely.

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