Stored-Product Pests

These pests feed on fruits, vegetables, grain and animal feed, which are stored in cupboards, pantries, warehouses and the like. Descriptions of these pests and control measures for each are found on this page.
As with the format of the website, the common name of each pest is followed by its scientific name in parentheses.

Beetles

From L-R: Merchant grain and sawtooth grain beetles. Note the prominent jagged or sawtooth edge of the thorax on both animals, however, the merchant grain beetle has a smaller, more rectangular head.

The sawtoothed grain beetle is about ⅒ inch long with a triangular head and wider region between the temple, which is behind the eyes and before the thorax. The adult is non-feeding, while the larvae are common in flour or processed foods that it feeds upon.'

Merchant grain beetle (Oryzaephilus mercator) is about ⅒ inch long and very similar to the sawtooth grain beetle, which also known as the flour weevil (Oryzaephilus surinamensis), but the merchant grain beetle is distinguished by its larger eyes and head, which is not as triangular as the sawtooth grain beetle. While the sawtooth grain beetle is flightless, this beetle is not. Both the merchant and sawtooth beetles can be identified by the conspicuous jagged-lined thorax, which can be seen in the images above. These pests feed on fruit, vegetables, chocolate, drugs, and tobacco.

Red floor beetle does not create a cocoon in the pupal state as do other insects.

Sponsored ❖ Ad

Red flour beetle (Tribolium castaneum) and other flour beetles, whose feeding larva are called grubs, undergo complete metamorphosis, infesting flour mills, warehouses, and other granaries. The red flour beetle, which is ¼ inch long, does not create cocoons in the pupal state.


]
From L-R: Warehouse beetle female is significantly larger than male.

Warehouse beetle (Trogoderma variable) is approximately ⅛ inch long, infesting stored foods, such as dried items (especially pasta) and animal feed, wheat and barley kernels, wholemeal flour, cornmeal, oatmeal, spices, nuts, cocoa and sugar products. Females are significantly larger than males.

The cowpea seed beetle, or weevil, has a prominent enlargement on the femur as indicated by the red arrow.

The cowpea seed beetle (Callosobruchus maculatus) has identified by a conspicuous protrusion on the femur and is sometimes incorrectly classified as a weevil. This pest, measuring ⅛ inch long, feeds on legumes and plays dead when feared.

Weevils

Weevils can be distinguished from beetles by the presence of an elongated snout found on the head.

The rice weevil has wings for flight and can be distinguished from the granary weevil by its reddish brown marks on its elytra.

The rice weevil (Sitophilus oryzae), with four, reddish, pale spots on its wings covers, plays dead when distributed, mimicking the cowpea seed beetle. This pest is about ⅛ inch long, damaging stored grains during its feeding and reproductive habits.

The grain weevil is similar in appearance to the rice weevil without the hind spots.

The grain or granary weevil (Sitophilus granarius), which is flightless and does not forage for food in the wild, but prefers stored grains, such as rice, corn, and oats found in pantries, warehouses, and granaries. This weevil is about ⅕ inch long and fakes death when disturbed.

Flying pests

 
The Indianmeal moth with scaly wings lives about 4-6 weeks.

The Indianmeal moth {Plodia interpunctella) adults don't feed, unlike the larval form, which causes damage to foodstuffs with silken webs of their habitation. This moth has a width of approximately ¾ inch with wings spread apart. The wings are brownish to copper in color and iridescent.

 
The adult Angoumois grain moth has pale brown and yellow wings.

Angoumois grain moth (Sitotroga cerealella), pronounced ahn-goo-mwa, is approximately ⅔ inch in width and undergoes complete metamorphosis. The wingtips are pointed, unlike the Mediterranean flour moth, which has rounded wingtips. The moth overwinters in the larval form.

The Mediterranean flour moth is dull grey with black patches along its wings.

Mediterranean flour moth (Ephestia kuehniella), which are the most common of stored-food pests can be distinguished from the Angoumois moth by its rounded wingtips. Adults don’t feed, but larval form feeds on grain, processed foods, candies, and fruits, which is similar to the feeding habits of Indianmeal moth larvae.

Pest Control

The lids and coverings of food and animal feed should be tightly sealed and spills should be cleaned up promptly. Birdfeed should be tightly sealed and kept away from human foodstuffs. Metallic storage containers are recommended over cardboard and paperboard which provide greater protection against the boring action of this type of pest.

The use of pheromone traps, which fool males Indianmeal moths, are highly effective. (Females moths typically produce sex pheromones.) Aggregation pheromones and food lures are also available for stored-product pests.

Sponsored ❖ Ad