Stored Product Insect Page*
Indian Meal Moth
Cigarette Beetle
Drugstore
Beetle
Confused Flour
Beetle
Lesser Grain Borer
Rice Weevil
Saw-toothed Grain
Beetle
Bean Weevil
Warehouse Beetle
Dried
Fruit Beetle
Secondary
Insect Pests
More
Information
Indian meal moth (Plodia interpunctella)
Appearance: The moth has a wing expanse of 14-20 mm. When at rest with closed wings, it is 8-10 mm long. The outer halves of the forewings are bronzy; the inner halves light gray to ochre yellow. The caterpillars are yellowish-white, sometimes reddish or greenish, with a brown head; they grow to a length of 17 mm.
Life History: The female deposits between 60 and 300 eggs, singly or in groups, on suitable nutrients. The grown caterpillars are active spinners; before pupation, they leave their food sources and climb up walls. Pupation occurs in a cocoon. The life cycle depends on temperature and is 2-6 months in Central Europe; in warm climates it can be completed in 3-4 weeks.
Distribution: World-wide
Damage: In warehouses, silos, mills, food processing plants and households, a large number of dry vegetable materials are infested; for example dried fruit, in
particular figs, groundnuts, almonds, cocoa beans, marchpane, various seeds, herbs, etc.; more seldom: grain and grain products, whereby only the germs are
eaten.
Cigarette beetle (Lasioderma serricorne)
Appearance: 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 4mm.
Life History: The female deposits 20-100 eggs singly on the infested goods over a number of days (at temperatures of over 68º F). After about 7 days, the very mobile larvae emerge; as they grow older, they become less mobile and pupate in a cocoon of food or waste particles after about 6-10 weeks. 5-14 days later, the beetle emerges. The total development period is 8-13 weeks. The adults are strong flyers and are active in subdued light at temperatures above 65º F.
Distribution: World-wide. They are frequently carried from warmer areas to temperate zones, where they can only survive in warm storages.
Damage: 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 (Stegobium paniceum)
Appearance: The beetle is 2-4 mm long, 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 antenna segments are particularly long. The larvae grow to a length of 5mm.
Life History: The female deposits 20-100 eggs on suitable nutrients, either singly or in clusters. The tiny young larvae can penetrate even the finest cracks, for example, in foodstuff packaging; in the substrate they then form a cocoon of nutrient particles, in which also pupation takes place. The entire development
period at 63º F is about 200 days, but only 70 days at 83º F.
Distribution: World-wide
Damage: An important household and warehouse pest, particularly when infested goods are left undisturbed for longer periods. The larvae are omnivorous and are found in all possible vegetable substances such as bakery goods and other flour and cereal products, herbs, spices, oilseed cake, etc. When badly infested, solid products are full of small round holes. The beetles do not feed.
Confused flour beetle
Confused flour beetle (Tribolium confusum)
Appearance: A slim beetle of 3-4 mm length, of uniform red-brown to black color. Remark to T. confusum: the segments of the antennae gradually broaden towards the tip.
Remark to T.casaneum*: the antennae end in three-segmented clubs. The slim, freely-mobile larvae are whitish to yellow-brown and grow to 5-6 mm in length.
Life History: The eggs, which are laid loosely on the stored product, are not readily discernible; the female deposits eggs for a period which can exceed 1 year, 350-400 eggs on average. The total development period is 7-12 weeks, depending on temperature; the larvae pupate loosely in the infested goods. Sensitive to cold; high humidity favors development. The beetles seldom fly, and can live more than 3 years.
Distribution: All parts of the world; in cooler climates, restricted to warm storages.
Damage: Beetles and larvae feed on a very wide variety of dry vegetable substances, for example, milled cereal products, groundnuts, cocoa beans, legumes, spices, dried fruits, tapioca, oilseed cake, etc. A frequent mill pest; badly infested flour has a sharp odor and turns brown; its baking properties are damaged. This pest an also attack undamaged wheat kernels.
Lesser grain borer (Rhyzopertha dominica)
Appearance: 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 three last segments of the antennae form a loose club. The larvae are white, similar to grubs, and have brown head capsules; the white pupal stage is passed inside the grain kernel.
Life History: In sufficiently warm climates, the beetle can fly well. A female deposits 300-500 eggs in grain and similar crops. The larvae can eat their way into grain kernels, and also pupate there. Development is only possible above 73° F; the development period is approx. 4 weeks at 83° F.
Distribution: In warmer countries. It is carried into the temperate zones in goods, where it can only survive in warm warehouses.
Damage: Mainly attacks wheat, rye, corn, rice and millet. Badly infested wheat takes on a honey-like odor. Also attacks whole kernels as a primary pest. Both larvae and beetles bore into grains; irregularly-shaped boreholes are made and the flour produced by boring appears on the surface. Also attacked are beans, lentils, chick-peas, dried potatoes, tapioca and herbs.
Rice weevil (Sitophilus oryza)
Appearance: The appearance of this weevil is similar to that of the granary weevil; it is however smaller (2.3-3.5 mm long), and differs from the granary weevil in that it has four reddish spots on the brown wing covers.
Life History: Develops within the kernel of grain, like the granary weevil; requires greater warmth than the granary weevil as it first develops at temperatures of above 55° F. Only few weevils survive the winter temperatures of the temperate zones; in tropical climates, the development of a brood may take only 1 month. The weevil can fly; in hot countries, the rice weevil flies to the fields and lays its eggs on cereal crops.
Distribution: World-wide, through cereal trading. Of great importance in tropical and subtropical countries.
Damage: A dangerous stored grain pest in warmer countries; it infests all types of grain. 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; often found together with granary weevils.
The maize weevil (Sitophilus zeamais Motsch.) is very similar to the rice weevil, but larger (3.3-5 mm), and the reddish markings on the wing covers are more clearly defined. Otherwise, as for rice weevil.
Saw-toothed grain beetle (Oryzaephilus surinamensis)
Appearance: A slim beetle, 2.5-3.5 mm long, dark brown; neck shield has two deep longitudinal grooves and 6 sharply-pointed projections on each side. The slim, whitish-yellow larvae are freely mobile and grow to a length of 3.5-4 mm; the pupa lies free or between adhering food particles.
Life History: The female deposits an average of about 150 eggs loosely in the infested goods. The total development period is 3-10 weeks, depending on temperature, nutrition and moisture; the lower development boundary is approx. 65° F. In the temperate zones, the beetle can survive the winter and live to an age of about 3 years.
Distribution: World-wide
Damage: Found in warehouses, silos, mills, food-processing plants; infests grain and grain products, flour, oats, semolina, pearl barley, malt, whole meal and other vegetable stocks such as feeds and dried fruit. In granaries, it is usually found as a secondary pest together with other grain pests; is, however, occasionally found alone, as primary pest.
Bean weevil (Acanthoscelides obtectus)
Appearance: The weevil is 3-5 mm long, yellow-green to olive, mottled with darker brown and gray; the end of the abdomen is yellow-red. The grub-like white larvae are hairy and grow to a length of up to 4mm.
Life History: The female lays an average of 40-50 eggs loosely between the beans; in hot countries, also in the ripening pods in the field. The larva develops in the bean; several can develop in one bean. Before pupation, the larva prepares a circular exit hole which remains covered only by the skin of the seed ("window").
Distribution: In most warm countries. In the temperate zones mainly in stores.
Damage: Attacks all pulses, particularly beans. Can reproduce repeatedly in dried pulses in store.
Warehouse beetle
(Trogoderma variabile)
Appearance: The adult beetle is about 1/8 inch (3.2 mm)
long and is brownish black with mottled patterns of brown on black with numerous
hairs present. The larva is approximately 1/4 inch (6.3 mm) long and
varies in color from a yellow-white to a dark brown depending on its age.
The larva possess two major type of setae; hastisetae, the spear-headed shafts
with numerous barbs; and spicisetae, the slender, elongate structures resembling
a rat tail in shape and bearing many sharp pointed hairs. The larvae has
about 1,706 hastisetae and about 2,196 spicisetae. Okumura (1967) reports
enteric irritation in two infants that swallowed the larvae of Trogoderma in
infested cereal, likely caused by hastisetae.
Life History: The male has five molts and the female six
molts before pupation. At 90° F/32.2° C and 50% relative humidity the
eggs hatched in six days. The life cycle from egg to adult can be
completed in 32 days.
Damage: Feeds on seeds of all kinds, dead animals,
cereals, candy, cocoa, cookies, corn, corn meal, dog food, fish meal, flour,
dead insects, milk powder, nut meats, dried peas, potato chips, noodles,
spaghetti, and dried spices. Prefers such foods as barley, wheat, mixed
animal feeds, processed grains, some grocery products, and pollen.
Distribution: Throughout the US.
For further information on the setae, go to "More
Information".
Dried
fruit beetle (Carpophilus hemipterus)
Appearance: The dried fruit beetle is 1/8 inch/3 mm in
length. It is somewhat oval and black in color with two large conspicuous
amber-brown spots at the posterior tips, but these spots may run together to
form one large spot. The antennae or legs are reddish or amber in color,
and the tip is knob-shaped. A characteristic that distinguishes the sap
beetles from most other beetles is the very short wing covers which expose the
tip of the abdomen.
Life History: The eggs are laid on the outside of the
fruit while it is still on the trees or while it is drying on the trays in the
open before it reaches the packing sheds. Thus, the fruit is infested
before actually arriving at the warehouses. The larval period extends from
four weeks to four months; the pupal stage runs for approximately two
weeks. The mature larvae are about 1/4 inch/6 mm long with the head and
tip of the tail a rich amber brown. The active larvae are covered with
long hairs and have two large tubercles at the extreme posterior end of the
abdomen and two smaller tubercles just in front of the larger ones. The
entire life cycle can take as little as 15.8 days, with many generations per
year.
Distribution: Can be found wherever fruit is grown.
It has been recorded from dried figs, plums, peaches, apricots, bananas, drugs,
nuts, bread, biscuits, grain, etc., especially when moist and decaying.
* Thanks to Degesch America for the color pictures.
