Stored Food Beetles


Several insects commonly infest home-stored foods, such as grains, flour, nuts, spices, packaged herbs and dried fruit. If infestations are prolonged, foods may be seriously damaged and may need to be discarded. Many people will discard food products that are even lightly infested by insects. These insects typically pose little health hazard, although some species (notably carpet beetles), can produce irritation or allergic reactions.

Whole Grain

Granery Weevil

A weevil of 3-5 mm length; black-brown (red-brown shortly after hatching); the head ends in a slightly curved proboscis; the neck shield has depressed markings and is almost as long as the longitudinally-grooved wing covers.

The granary weevil is the main stored grain pest in countries of the temperate zones. Damage is caused primarily by the larvae but also by the adults.

Prefers wheat and rye, but also feeds on corn, barley, millet, rice, and buckwheat. After mass infestation the grain becomes damp and warm leading to infestation of secondary pests and mold.

Rice Weevil

Similar in appearance to the granary weevil but is smaller (2.3-3.5 mm long) and has reddish spots on the brown wing covers.

A dangerous stored grain pest in warmer climates; it infests all types of grain and is often found together with granary weevils.

The larvae can also develop in farinaceous products, buckwheat, peas, acorns, chestnuts, and cottonseed; the weevil also feeds on flour, hemp-seed, biscuits, waffles, white bread, and tobacco.

Lesser Grain Borer

A beetle of 2-3 mm length, red-brown to black-brown, slim, cylindrical in body. The hood shaped, rounded neck shield extends beyond the head; the spots on the shield gradually become smaller towards the rear. The larvae are white, similar to grubs, and have brown head capsules. Both larvae and beetles bore into the grain.

The lessor grain borer mainly attacks wheat, rye, corn, rice and millet. Also attacked are beans, lentils, and chick-peas.

The eggs are deposited on the outside of the kernels. Badly infested wheat takes on a honey-like odor. Also attacks whole kernels as a primary pest. Irregularly-shaped boreholes are made and the flour produced by boring appears on the surface. The larvae bore their way into kernels which they only leave again as adult beetles.

General

CIGARETTE BEETLE

A 2-4 mm long, squat beetle, almost hemispherical, reddish-brown and covered with fine hairs; the head is hidden under the domed neck shield; the wing covers have no markings. The antennae are saw-like; the segments are practically identical. The larva is very hairy and grows to a length of up to 4 mm.

They are frequently carried from warmer areas to temperate zones, where they can only survive in warm storages. Attacks not only leaf and processed tobacco but also a large number of other dry vegetable products such as herbs, oilseed cake, rice, cocoa, groundnuts, figs, dates, paprika, etc. Practically all damage is done by the larvae.

DRUGSTORE BEETLE

A 2-4 mm long beetle, of reddish-brown color, with fine hairs on its oval body. The head is hidden under the uniformly-domed neck shield; the wing covers are finely patterned with lines of dots; the last three antennal segments are particularly long. The larvae grow to a length of 5 mm.

They have a worldwide distribution and can be more commonly found in warmer climates. They are similar in appearance to the Cigarette beetle, but are slightly larger. Additionally, Drugstore beetles have antennae ending in 3-segmented clubs, while Cigarette beetles have serrated antennae (notched like teeth of a saw). The Drugstore beetle also has grooves running longitudinally along the elytra, whereas the Cigarette beetle is smooth.

Their larvae are small, white grubs, and are responsible for most of the damage that this species can cause. As their name suggests, Drugstore beetles have a tendency to feed on pharmacological products, including prescription drugs. The beetles and larvae are dangerous pests in the dried fruit industry. But they also infest oilseeds, dried vegetables and herbs.

SAW-TOOTHED GRAIN BEETLE

A slim beetle 2.5-3.5 mm long, dark brown; neck shield has two deep longitudinal grooves and six sharply-pointed projections on each side. The slim whitish-yellow larvae are freely mobile and grow to a length of 3.5-4 mm.

Found in warehouses, silos, mills, and food processing plants; it infests grain and grain products. In granaries, it is usually found as a secondary pest together with other grain pests but is occasionally found alone as the primary pest.

Moist Grain Products

MEALWORM BEETLE

The adult is a dark brown or black beetle about 12mm long. Its thorax is finely punctured, and its wing covers are longitudinally striated or grooved. Both yellow mealworms and dark mealworms have well-developed wings and are attracted to light. Yellow mealworm adults are shiny, dark-brown or black, whereas dark mealworm adults are dull, pitchy black.

Mealworms have a smooth, highly polished, shiny, elongate, hard, cylindrical (wormlike) body about 3mm thick and up to 32mm long at maturity. Young larvae are white, darkening with age. Larvae of yellow mealworms are honey-yellow, while dark mealworms are dark-brown.

Mealworms are among some of the largest insect pests of stored products. Their common names are derived from the color of the wireworm-like larvae. Both yellow and dark mealworms are in the genus Tenebrio, meaning "darkness," owing to the nocturnal habits of the larvae. Believed to be of European descent, both insects are cosmopolitan, with the yellow mealworm more prevalent in the cooler northern states.

CADELLE

A slim, flat, 6-11 mm-long beetle, dark brown to black; ventral side, antennae and legs are red-brown. A particular feature is the waisting between wing covers and neck shield, whose outer front corners extend toward the head.

A serious pest in the tropics, found in mills, silos, and warehouses, on grain, mill products, and feeds. Irregular borings are found in kernels; germs are preferred.

The dirty-white larva, has a black head, behind this a black shield, two black hooks at the end of the body and long body hairs.

Dry Cereal Products

RED/CONFUSED FLOUR BEETLE

A slim beetle of 3-4 mm length, of uniform red-brown to black color. Beetles and larvae feed on a very wide variety of dry vegetable substances, such as, milled cereal products. A frequent mill pest; it can also attack undamaged wheat kernels.

Besides grain and grain products it infests foodstuffs and animal feeds of all kinds; also spices and drugs. Badly infested flour has a sharp odor and turns brown; its baking properties are damaged.

KHARPRA BEETLE

An oval beetle 2-3 mm long, dark brown with smudgy yellowish-brown and reddish-brown transverse strips on the wing covers and covered with fine hairs.

The yellowish-brown, spindle-shaped larvae grow to a length of up to 5 mm. They have thick, reddish-brown hairs, with characteristic bunches of tail hairs growing out of the rear end. They have barbed arrow-hairs with which they adhere easily to sacks and transport containers and are thus widely disseminated. They can exist without feeding for up to 3 years.

The larvae is a very serious stored product pest but the beetle itself does no damage. It is found in warehouses, silos, mills, breweries, and malt plants. It attacks all types of grain, malt, cereal products, and pulses. Grain kernels are often hollowed out until only the husk remains.

FLAT GRAIN BEETLE

A small flattened, oblong, reddish-brown beetle of 2 mm length, with elongate antennae about two-thirds as long as the body.

Prefers grain and grain products but damages also many foodstuffs and animal feeds.

This insect is not a primary pest of stored grain, and the adult is unable to survive in sound uninjured grain. It follows up the attack of more vigorous grain pests and infests grain and meal that are in poor condition.