Rice Weevils – are an important grain pest in North America, mainly in the South and along the Gulf Coast.
Granary Weevils – are similar in appearance and habits but prefer the cooler areas of the northern part of the continent. They are both primary and secondary feeders.
These WEEVILS have a distinctive physical appearance, namely a cylindrical body and a long thin downward pointing snout.
The adult RICE WEEVIL is 2 to 3 mm long, dull reddish brown to dark brown in color; it can fly and is attracted to lights.
The adult GRANARY WEEVIL is 3 to 5mm long, shiny reddish-brown to black in color; it cannot fly and is not attracted to lights.
The creamy white larvae of these beetles are very small, legless, humpbacked grubs with brown-black heads. The larvae are not seen usually because they spend their entire lives inside a kernel of grain. The size of the adult WEEVIL depends on the size of the grain in which it developed.
The entire life cycle, from egg to adult, is 4 weeks for the RICE WEEVIL, and 4-7 weeks for the GRANARY WEEVIL. The adult RICE WEEVIL can live 3-6 months; the GRANARY WEEVIL lives 7-8 months.
The larvae prefer to feed on whole grain, seeds and hard cereal products. They will infest wheat, barley, corn, rice, nuts, sunflower seeds, popcorn, beans, bird seed; they will attack also hard cereal products such a macaroni, cereals, caked flour, dry pet food.
Effective control requires good sanitation, the proper storage of susceptible materials and pesticide applications. Infestations may be eliminated and/or prevented by:
1. Locate the source of infestation. Examine the underside of food containers for adult WEEVILS and holes in the packaging.
2. Grain, seeds, caked products can be poured into a large bowl for about 10 seconds, because the insects will remain motionless and can be difficult to see until they start moving.
3. Unsalvageable infested foodstuffs should be sealed in a plastic bag and disposed of outdoors. Susceptible food products should be stored in sealed glass or plastic containers.
4. Kitchen cabinets, dry food storage rooms and areas under stoves, refrigerators and other places where food debris may accumulate should be vacuumed. In commercial establishments, areas under pallets, shelves and platforms should be cleaned regularly.
5. Seldom used food products should be purchased in small quantities to avoid prolonged storage. Foodstuffs should be rotated on a first-in, first-out basis. Commercial establishments should use metal shelving – rather than wooden pallets – for long term storage of food goods.
6. Areas with evidence of activity should be treated with residual sprays. Space treatments are useful in heavy infestations. Infested salvageable commodities in commercial bulk storage should be fumigated.
7. Heat treatment or freezing may be useful when these control methods are not feasible. Homeowners may heat infested products in an oven to 140F for 30 minutes to kill all stages. Freezing infested materials at 0F for 2 weeks will also control these pests. In mills and food plants, most stored-product pests can be controlled by raising infested commodities to 130F for about 30 hours, using unit heaters with good circulation capabilities that will maintain the required temperature.
BEFORE USING ANY PESTICIDE, READ THE LABEL CAREFULLY
Also make sure you check out Stored Product Insects for more information about weevils.