PEST ON STORED PRODUCTS – Pest Control Identification study materials

RICE WEEVIL Sitophilus oryzae (Family: Curculionidae, order: Coleoptera)

It is a small weevil about 3 millimeters in length with head protruded into a down ward snout like structure and reddish brown with four pale spots on the elytra. Eggs are laid in cavities made on the grain by the adult female.  The whole developmental life is being spent inside the grain. 

They are attacking stored cereals like rice, wheat, sorghum, Bajra and maize. But, rice is the main host for this weevil. 

GRANARY WEEVIL Sitophilus granarius (Family: Curculionidae, Order: Coleoptera)

         It is one of the oldest known insect pests of stored grain.  It is a polished, chestnut brown or blackish weevil which is very similar to rice weevil.  Adults have distinct beak and entirely dark elytra. Pronotum elongated.

Female weevil lays eggs in a slit like opening made in the grain and covered with a gelatinous mass.  They feed on rice, wheat, sorghum, Bajra and maize. 

MAIZE WEEVIL Sitophilus zeamaize (Family: Curculionidae, Order: Coleoptera)

           It is a serious pest of stored maize in many parts of the world.  The life history of S. zeamaize is identical to S. Oryzae. Rostrum is prominent. Thorax is large and conspicuous and dark brown in colour.

Females lay eggs inside the grain by chewing a minute hole and seal with a secretion. They mainly attack maize, sorghum, rice and other cereals in storage. A thin tunnel is bored by the larva from the surface to the inside of grain.  Circular exit holes on the surface of the grain kernel are characteristics. 

LESSER GRAIN BORERR hizopertha dominica(Family: Bostrichidae, Order: Coleoptera)

                    It is also known as Australian wheat weevil. This beetle is a strong flier and spreads with great speed and also found attacking wheat in the field.  It is a small cylindrical beetle, 2-3 mm in long and dark brown in colour with a roughened surface. Head is turned down with a hood shaped pronotum. The antennae end in a prominent club. Adults are long lived.  

It feeds on wheat, paddy, dry fruits, flour, maida, maize and other stored food stuffs including cassava.  Both larvae and adults feed on the grains usually from the outside. Adults are more harmful than grubs and they destroy more than they eat.

KHAPRA BEETLE Trogoderma granarium (Family: Dermestidae, Order: Coleoptera)

                        Its habit of congregation in cracks and crevices of bricks, masonry and wood storage structures give it the name ‘khapra’. Adults are oval shaped, 2-3 mm long, has grey and light brown markings and emarginated eyes. Head is hidden beneath hood like pronotum and is darker than elytra. Male is smaller than female. 

Its larval stage is most destructive. It spreads first on the superfluous layers of the grain, later penetrates but cannot enter very deep into the heap of grain. They usually confine to the upper (50cm) layers of the heap. Khapra beetle feeds on corn, malt, barley, wheat, maize, oat, cotton seed, dry fruits, dried milk products, groundnut, pulse products and oil cakes.  The larvae bore in the stored cereals and pulses.  

RED FLOUR BEETLE Tribolium castaneum, Tribolium confusum (Family: Tenebrionidae, Order: Coleoptera)

There are two species of Tribolium commonly occurring, but it is difficult to distinguish one from the other.  Adults are reddish brown in colour, 3-4 mm in length with distinct head, thorax and abdomen. Antennae well developed, the last few segments are much larger than the preceding ones.  The terminal segments of antennae suddenly enlarge in T. Castaneum and where as in T. confusum antenna is enlarged gradually towards the tip. The life history of these two species is almost similar.  

Tribolium does not infest whole grains, but only broken grains and milled products particularly bran and flour.

SAW-TOOTHED GRAIN BEETLE Oryzaephilus surinamensis (Family: Silvanidae, Order: Coleoptera)

This is a flat, grayish beetle with a superficial resemblance to a head louse.  It is commonly known as saw tooth beetle because of its six saw tooth like projection present in the thorax region. The life cycle lasts far about 6 to 10 months. It measures about 2.5 mm long.  It is a fairly tough-insect.

Saw-toothed grain beetles attack mainly the starchy food items in flour mill and grocery stores. It feeds on rice, grain products, dry fruits, nuts, seeds, yeast, sugar, candy, tobacco, snuff, dried meat, processed plant materials.

LONG HEADED FLOUR BEETLE Lathetius oryzae (Family: Tenebrionidae, Order: Coleoptera)

This pest is found in arid, semi arid and costal regions. This is generally found in association with Tribolium.  Adult beetle is slender, flattened, and slightly lesser than 3 mm in length with pale yellow or pale brown in colour. It attacks the stored grains and grain products in granaries.

CADELLE BEETLE Tenebroides mauritanicus (Family:Trogosositidae, Order:Coleoptera)

Adult beetles are elongate, oblong, flattened and shining black or reddish brown in colour.  It is about 1.27cm in length and is the largest insect among the stored grain insect pests.

Damage the grains and grain products.

FLAT GRAIN BEETLE Laemophlaeus minutus (Family: Cucujidae, Order: Coleoptera)

Flat grain beetle is a smallest beetle found in stored grain pests.  It is not a primary one. The adult is a flattened, oblong beetle with slightly reddish brown in colour. Antennae are long. It is equal to 2\3 of its body length.

It attacks the grain which is already damaged by other pests.

YELLOW MEAL WORM Tenebrio molitar (Family: Tenebrionidae, Order: Coleoptera)

The yellow meal worm is named mainly due to its honey yellow colour. Adult beetle is about 1.25 cm in length with well developed wings, less or numerous punctures found on the body of the beetle.   

It attacks flour material like maida, atta, bran, rye, slices of potato and broken kernels.

TOBACCO BEETLE/ CIGARETTE BEETLE Lasioderma serricorne (Family: Anobiidae, Order: Coleoptera)

Adults are small, oval, reddish yellow beetles about 3-4 mm long. The females are larger than males.  Adult longevity is 2-6 days. The beetle rests with the head and neck bent down ward. If it disturb it shows feigning death.

The cigarette beetle is the most destructive insect pest found on stored tobacco (Stored leaf and Cigarettes). It also feeds on ginger, dried fruits, pepper, coriander, Turmeric, mustard, cacao, groundnut, peas, beans, flours and other food stuffs.

DRUGSTORE BEETLE Stegobium paniceum (Family: Anobilidae, Order: Coleoptera)

    Drugstore beetle is similar to cigarette beetle in shape and its behaviour. The length of the body is about 2.5 to 3.5 mm. Females are heavier than males.

 It is found in drug and pharmaceutical stores. The drugstore beetle attacks dry plant products like uncured tobacco, pepper, leather and textile materials.

INDIAN MEAL MOTH Plodia interpunctella (Family: Phycitidae, Order: Lepidoptera)

Adult moth is small distinctive, 5 to 10 mm long with wings held close together when sitting. The anterior one third of the wing is grayish and the outer two third has a coppery luster. So that when the moth is sitting at rest, the wings appear to be marked with a prominent brown band. The hind wings are uniform silvery gray and fringed with hairs.

It damages meals, flours, dried fruits, grains, soybean, herbs, nuts and dead insects. 

DRIED FRUIT BEETLE  Carpophilus hemipterus (Family: Nitidulidae, Order: Coleoptera)

Adults are small, flat beetles, 3-4 mm in length, having yellow patches on the elytra. Eggs are laid amongst the dried fruits.  Larva is campodeiform and white or yellow in colour. Bear two small pairs of horns at end of the abdomen.

It is a pest on dried fruits, currants, raisins, fig, cotton bolls, maize cobs, copra, cocoa beans and groundnuts.

ANGOUMOIS GRAIN MOTH Sitotroga cerealella (Family: Gelechiidae, Order: Lepidoptera)

    It is a small straw coloured delicate moth with narrow fringed wings. The hind wings are margined with long hairs, their tips are elongated. It is a fragile insect not capable of penetrating deep into the mass of the grain. 

Females after copulating lay eggs on the grove of the grains or any place in the storage godown.  Each female lies on an average 106 to 160 eggs. The eggs are creamy white, cylindrical and cigar shaped.  Eggs hatch in about 3 days. Larvae feed on endosperm and enter into the seed after five days. Five pairs of pro legs are present in the abdomen. Fully grown larva spins cocoon and pupates inside.  The pupal period is of seven days. Total life cycle is completed in 32 days.

Angoumois grain moth is an important pest of stored and field grain. It damages wheat, maize, sorghum, barley and other grains. The moth breeds in grain in threshing yard granaries.  

RICE MOTH Corcyra cephalonica (Family: Gelechiidae, Order: Lepidoptera) 

This is nocturnal in habit and rests on shady place in stores.  The adult moth is large. The forewings are broad with distinct shoulders. The hind wings have fringed hairs and grayish brown in colour.

Oviposition begins mostly at night on rough surfaces few hours after copulation. The eggs may be deposited on walls, flour sacks etc. Lay 100-150 eggs.  Egg period is 4 -7 days. The yellowish caterpillar feeds concealed in a silken case to which are also attached grains and particles of frass. There are eight larval instars.  The larva damages the stored food by moving feeding and leaving silken threads. The threads are left over on the food which later forms dense and tough webbings. The larva also enters the food where silken galleries are formed.  The larva is hidden inside the densely webbings where it is difficult to find its presence. Larval period is 21- 41 days. Pupal period 9-14 days.

It destroys a variety of stored products such as groundnut, dried fruits, cocoa, biscuits and oil cakes.

ALMOND MOTH Cadra cautella (Family: Phycitidae, Order: Lepidoptera) 

This is a grayish moth with transverse stripes on wings. Eggs are laid on the food stuff.  Egg period is 5-10 days. Larva spins silken tubes in the food material. Larval period 40-50 days.  Pupation occurs in a silken cocoon.

    Serious pest on stored wheat, other cereals, ground nut, dried fruits, dates, stored vegetables, oil cakes, seed bran, cocoa beans, soybeans, raisins, dried apples, lac, dried mango, almond, walnut berries, fig, tamarind seed, mango pulp and dry garlic bulbs.

HUMP SPIDER BEETLE  Gibbium psylloides (Family: Ptinidae, Order: Coleoptera)

Adult beetle is oval and its back portion is bulging like hump. It is 2.1 mm to 3 mm in length. Back is covered with red shining velvety hairs whereas head and thorax entirely bare and shinning. Head bent downwards.   Wings are shining and smooth. Its legs are spider like and cannot fly but crawl. Total life cycle from egg to adult takes about 45 days.

Hump spider beetle attack flour, meal, seed and other stored products.

PULSE BEETLE Callosobruchus chinensis, Callosobruchus analis, Callasobruchus maculates (Family: Bruchidae, Order: Coleoptera)

Pulse beetles are dull coloured beetles with characteristic faint spots on the back and oval in shape. The body is covered with pubescences.  Head is small with pectinate or serrate antennae. The elytra are truncate i.e., do not cover the entire abdomen. Legs are short and the hind femora thickened. Adults can fly from the godown to the nearby fields where pulses are growing.

The female prefers smooth whole seeds for oviposition.  After the egg is laid female covers it for about 30 seconds during which it stick to the seeds. Eggs are laid singly but as many as 8 eggs could be glued to a single seed. Female can lay on an average of about 63-90 eggs over a period of 8 days. The freshly laid eggs are translucent, smooth and shinning but become pale yellowish or grayish with age. 

Eggs hatch in about 4-5 days. The first instar grub bears a large spine on either side of the first abdominal segment. The grub turns at right angles after boring into seed and forward horizontally. The grub undergoes four moults before pupation.  The larval period lasts for about 18-20 days. Full grown grub is 6 mm long. The adult is about 3 mm in length. Complete development from egg to adult takes an average of 22-23 days. 

Pulse beetle is a well known pest of stored legume seed.

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