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8. SILVANIDAE
The Silvanidae are a small family closely related to the Cucujidae. The adults are narrow and distinctly flattened, possess 11 -segmented antennae with a compact club. The elytra completely cover the abdomen, and there are five visible abdominal sternites. The tarsi are all 5-segmented. Most species are probably predacious, but two species of Oryzaephilus are of great importance as secondary pests attacking broken or milled cereals and oilseeds, while Ahasverus advena Waltl, the "foreign grain beetle", probably feeds on moults and refuse, and is rarely found in grain which is in good dry condition. Another closely related species, Cathartus quadricollis (Guerin-Meneville) which resembles the saw-toothed grain beetle, but differs by the square prothorax which lacks the six large teeth on either side, is one of the most common beetles in stored corn in the Southern USA, and on damaged and exposed ears in the field. Its form and habit are also similar, while the larvae have the annoying habit of devouring the germs of the seeds in which they breed.
(i) Oryzaephilus surinamensis (L.), The saw toothed grain beetle.
Small (2.5-3 mm) brown beetle; distinguished by serrated lateral margins of thorax.
The eggs are laid loose amongst the substrate or tucked into creases in the grain. The pale yellow, elongate larva passes through four instars feeding and moving freely and eventually pupates within a cocoonlike structure of small grains or food particles. After a preoviposition period of 54 days the female lays some 375 eggs (at 30°C) over a life-span of 6-8 months but may be prolonged at low temperatures. The adult may overwinter in temperate areas in the fabric of the building or granary.
The life-cycle can be completed over 20°C to 37.5°C, the optimum range being 31-34°C. Development is relatively rapid and is completed in 22 days at 30°C and 68 days at 20°C (at 70% R.H.).
The species is very tolerant of low humidities and even at 30°C and 10% R.H., larval mortality is less than 15%.
The adults rarely fly and during the day they tend to hide in cracks and crevices which enables them to escape the harmful effects of unfavourable temperatures and insecticide treatments. Aggregations occur at the edges of and in the dampest and warmest parts of a grain bulk and may contribute to grain heating.
O. surinamensis is a cosmopolitan secondary pest of cereals, mainly milled products such as flour, meals, breakfast foods, stock and poultry feeds, copra, confectionery and dried fruits.
(ii) O. mercator (Fauvel), The merchant grain beetle.
Small (2.5-3 mm) brown beetle: may be distingguished from O. surinamensis which it closely resembles, by the eye diameter being larger than the temple region behind the eye, the more triangular head and generally darker and slightly larger.
Life-history and biology similar to that of 0. surinamensis but O. mercator has a lower rate of increase because of its lower fecundity and slower development. Thus, the female produces an average of only 200 eggs and development takes 23 days at 30°C and about 100 days at 20°C (both at 70% R.H.). Additionally, the species is less tolerant of low humidities and extreme temperatures than O. surinamensis and is therefore less important in temperate regions.
O. mercator is more abundant in oilseeds, cakes and dried fruit than cereals and milled products although it will thrive in the latter.
(iii) Ahasverus advena (Walt!), The foreign grain beetle.
Small (2-3 mm) brown beetle: prothorax squarer than O. surinamensis and has only one prominent tooth at each apex.
Generally regarded as a mould feeder attacking a wide range of commodities such as damp cereals or cereal products, copra, groundnuts, oilseeds and cakes, dried fruits, etc., but can breed in clean cereals provided that yeast or germ is present. At 25°C and 70 R.H. development is completed in 35-40 days but the species fails to breed below 60% R.H.
A. advena, although cosmopolitan, is most abundant in tropical and warm temperate regions.
9. TENEBRIONIDAE
This is one of the largest and most important families of small to moderate sized beetles nearly always unicolorous black or dark brown with 11 segmented antennae (rarely 10-segmented) and are generally thickened or clubbed towards their apices. The elytra completely cover the abdomen, and there are five visible ventral abdominal segments. The front and middle tarsi are 5-segmented and the hind tarsi are 4-segmented. It is useful since it distinguishes members of this family from nearly all other stored products Coleoptera.
They are particularly abundant in the subtropics, where most species are saprophagous, feeding on organic debris, and are also well adapted to dry conditions. Many are carnivorous; cannibalism being common, some are predators and others require their diet to be supplemented with insect remains.
Almost 100 species have been recorded as stored product pests. Their size varies considerably from about 21 mm in Blaps mucronata to 2.8 mm in Alphitophagus bifasciatus. The larvae are cylindrical, generally sclerotized, yellow to brown, and compared with pests such as Sitophilus and Rhyzopertha, the adults are longer lived, producing eggs throughout most of their life and the larvae pass through many more instars.
(i) Tribolium castaneum (Herbs"), The rust-red flour beetle.
Small (2.3-4.4 mm) reddish-brown beetle. Antennae with distinctive 3-segmented club. Width of eyes (seen from below) about equal to the distance between the eyes. The lateral margins of the head are nearly continuous at the eyes.
The eggs, which are usually covered with particles and are laid singly. The larva, which is white to yellow and has rather obvious protruberances or horns on the terminal segment, passes through 6 or more instars. Newly emerged adults mate and start to lay eggs within 3 or 4 days. The adult may live for 14 months (average 9 months) and produces as many as 18 eggs per day during the first month of life when temperature, moisture and food supply are suitable. Although this high rate of egg production declines with increasing age the potential fecundity of any female may well exceed 1000 eggs. Both larvae and adults are cannibals and may consume eggs, young larvae and pupae.
The life-cycle can be completed over 20-42 °C but the optimum lies between 32-37.5°C. Development from egg to adult takes 22 days at 34°C (72% R.H.) and 50 days at 24°C (76% R.H.).
The adults fly readily at temperatures found 25°C and are generally more numerous on the grain surface. Although cosmopolitan, T. castaneum, with its relatively high temperature optima is a pest of tropical or warm areas while in temperate or cold regions, it may be replaced by T. confusum.
T. castaneum is a secondary pest of a wide range of cereals, cereal products, legumes, oilseeds and cakes, nuts, spices and animal products and is regarded as an extremely successful omnivore particularly abundant in warm and often dry conditions. Quinones secreted by the adults produce an unpleasant musty taint under high population densities.
(ii) T. confusum Jacquelin du Val. The confused flour beetle.
Small (2.6-4.4 mm) flattened, oval, reddish brown beetle. Antennae without a distinct club, but expand gradually. The width of eyes (seen from below) about one third of distance between the eyes. The head margins are expanded and notched at the eyes. The head and upper parts of the prothorax are densely covered with minute punctures. Elytra ridged lengthways and sparsely punctate between the ridges.
Life-history and biology essentially as for T. castaneum. However, T. consusum is less fecund than T. Castaneum and under favourable conditions lays only 14 eggs per day during the first month of life. The life-span is about 7 months but may exceed one year.
Development from egg to adult may be completed from about 19°C to 37.5°C, the optimum lies between 30°C and 34°C. The life-cycle is completed in 26 days at 34°C (72% R.H.) and in 54 days at 24°C (76% R.H.). Under identical conditions of temperature and humidity T. confusum develops more slowly than T. castaneum. Development may be prolonged at low humidities but mortality is little different from that at optimal conditions.
The adult seldom flies and the dispersal of the species is passive.
T. confusum is less susceptible to cold than T. castaneum and although cosmololitan more abundant in temperate regions. A wide range of cereals cereal products, nuts, oilseeds and their cakes are attacked.
Several other members of the genus are also troublesome on cereals and cereal products. T. audax (Halstead), the American black flour beetle, is commonly found both butdoors and in warehouses and is often confused with the European T. madens (Charpentier) which it resembles in appearance, biology and habits. Both are essentially similar to T. confusum, but are larger (3.55.2 mm) and black in colour. Another European import is T. destructor (Uyttenboogaart), a larger (4.5-5.5 mm) brown beetle which is not cold tolerant, and T. anaphe (Hinton) which is 3.6-5.1 mm long, brown, and is similar in biology to T. castaneum, but more susceptible to low humidities.
Because of the arrested development of some larvae at low temperatures T. madens appears better able to withstand cold conditions than the Tribolium species discussed. It is a secondary pest of some importance in granaries and flour mills in USA, Canada and eastern Europe.
(iii) Tenebrio molitor L. The yellow mealworm. Large (12-18 mm) polished dark brown to blask beetle. Thorax is finely punctured, and the wing covers are longitudinally striated or grooved.
The bean-shaped, white eggs, which become covered in particles of flour and dust are laid singly or in clusters. The active tarva are yellowish in colour except for the brown head, prothorax and terminal segment and may moult as many as 23 times- the number being influenced by temperature. The adults live for up to 3 months which is considerably less than most Tenebrionids, and lay some 280 eggs.
The optimum temperature for development appears to be 25°C and at 75% R.H. The life-cycle is completed in about 250 days and there is normally one generation per year in temperate regions. The adults, which are quite strong fliers, may be seen in light traps at night.
T. molitor is a cosmopolitan but minor secondary pest that is more abundant in temperate and subtropical areas than in the tropics. Found mostly in undisturbed residues in corners, under floors and under sacks, etc., and its presence is often indicative or poor hygiene.
(iv) Tenebrio obscurus F. The dark mealworm.
Large (12-18 mm) dull, pitchblack beetle.
Biology and life-history essectially the same as T. molitor. Adults live for two to three months and produce about 460 eggs over three months. The overwintering larvae usually begin to pupate before those of the yellow mealworm.
(v) Alphitobius diaperinus (Panzer). The lesser mealworm.
Medium sized (5.5-7 mm) blackish or very dark reddish-brown, beetle, resembling dark and yellow mealworms but much smaller. The eggs are generally stuck, in groups, onto a firm surface. The active cylindrical larvae, which vary in colour with increasing age from white to brown, pass through 8-11 instars and appear to require the presence of fungus for their proper development. The pupa, which is brown when mature, is found in a cell constructed by the larvae.
In a saturated atmosphere, the optimum temperature for development is approximately 32°C when development from egg to adult is completed in 46 days with 60% survival. At 16°C, development is extended to 97 days and survival is reduced to about 27%. Adult mortality is high and immature stages cannot survive in grain of 9% moisture content regardless of temperature and survive better in grain of 15% moisture.
A. diaperinus is a cosmopolitan secondary pest and is recorded from oilseed cakes and meals, cereal brans and meals, whole cereals and oilseeds. It is particularly abundant in damp out-of-condition grain and spillage and mostly occurs in poultry houses where it may be found in great numbers amongst the litter. It appears to act as a reservoir for avian leucosis.
(vi) Alphotobius laevigatus (F.), The black fungus beetle.
Medium sized (4.5-6 mm) black beetle. Differentiated from the lesser mealworm by the eyes being completely or nearly completely divided by a backwardly produced wide margin of the head. Lifehistory and biology similar to that of A. diaperinus. Requires damp and mouldy conditions for survival. It infests oilseeds, oilseed cakes and meals, cereals and cereal products and other commodities but is not found in poultry houses. It is less tolerant of cold than A. diaperinus and has a more tropical distribution.
(vii) Palorus subdepressus (Wollaston), The depressed flour beetle.
Small (2-2.5 mm) reddish-brown beetle. Head with sides strongly explanate and flexed upwards. A distinct ridge above the eyes covering anterior portion. Eyes large with vertical diameter exceeding horizontal diameter.
The egg, which is sticky when laid and usually covered in food is laid loose amongst the substrate. The cylindrical larva, which are transparent when yound and brown when mature, passes through 7-9 instars. The pupa is found within a cell amongst the substrate.
At 30°C and 80% R.H., the female produces some 2.5 eggs per day with a maximum of 650 eggs throughout most of her life span of about 6 months. The development from egg adult can be completed over the range 20-35°C; the optimum being 30-32.5°C. Development takes 36 days at 32.5°C and 124 days at 20°C and relative humidities of 70-80% appear to be the most favourable.
P. subdepressus is a cosmopolitan, but not abundant, secondary pest in the residues of damp and mouldy grain.
(viii) Palorus ratzeburgii (Wissman). "The smalleyed flour beetle"
Small (2-3.0 mm) somewhat oblong, flattened reddish-brown beetle. Head with sides not strongly flexed upwards while the ridge above the eyes is feeble and indistinct. The eyes are small and round. Biology and life-history generally similar to P. subdepressus. The female is more fecund and, at 30°C and 80% R.H., lays about 3.4 eggs per day.
The optimum temperature for development lies between 30°C and 32.5°C can be completed up to 37°C. The species develops quicker than P. subdepressus i.e. 22 and 69 days respectively at 32.5°C and 20°C (70% R.H.) and can tolerate drier conditions.
The small-eyed flour beetle is cosmopolitan but generally is more common and has a wider distribution than the depressed flour beetle. It breeds in grain and milled products and is frequently found in basements. However, both species appear to be of relatively minor economic importance.
(ix) Latheticus oryzae Waterhouse, Long headed flour beetle.
Small (2.5-3 mm) rather slender flattened, yellowish-brown beetle. Head extended in front of eyes. Antennae distinctive: short and thickened with a five segmented club.
The eggs, which are sticky when laid; are usually covered in floury particles. The free living larva is white and passes through 6-7 instars. The pupa is white and is found naked amongst the substrate. The slow moving adult lives for up to 112 days and lays about 300 eggs.
The optimum temperature range for development is 33-37°C with a minimum threshold of about 25°C. Development form egg to adult is completed in 29-37 days at 31 °C and 70% R.H. on sieved wheat.
L. oryzae is a cosmopolitan secondary pest of some importance in the tropics and sub-tropics but is of little significance in cold climates except in heated premises, because of its unusually high temperature preferences. Both damaged whole grains and cereal products are attacked and causes the same type of damage as the confused flour beetle. It has been recorded infesting wheat, rice, corn, barley, rye, flour and similar products.
(x) Gnathocerus cornutus (F.), The broad horned flour beetle.
Small (3-4 mm) reddish-brown beetle. Mandibles of male armed with a pair of broad, stout horns; edges of head expanded an strongly flexed upwards.
The egg, which is sticky when laid, is covered in floury particles. The free living larvae, which is yellowish-brown with a dark brown head and terminal segment, passes through 7-8 instars. The exarate pupa is yellow when young and brown when mature, and found loose amongst the substrate.
Females may produce as many as 1200 eggs over a period of 7-14 months. Development is possible over the range of 15-32°C while the optimum range appears to be 24-30°C and takes about 8 weeks. Low humidities extend the larval period without markedly increasing mortality.
G. cornutus is a cosmopolitan, but minor, secondary pest in flour mills and a scavenger in grain debris. It cannot tolerate low temperatures.
(xi) Gnathocerus maxillosus (F.). The slender horned flour beetle.
Small (3-4 mm) reddish-brown beetle, more slender than G. cornutus, with the life-history and biology being essentially similar. Development is possible over the range 20-35°C and takes 35 days at 30°C (91% R.H.) and 64 days at 23°C (93% R.H.).
This pest is of little economic significance and is mostly recorded on maize or groundnuts in the tropics and sub-tropics.
10. TROGOSITIDAE
The members of this family vary considerably in size, form and habits. Adults are obovate (egg shaped) to parallel without hairs or scales or at most with a few very short, microscopic hairs. The antennae are 11segmented and terminate in a 3-segmented club. Elytra completely cover the abdomen. Tarsi are 5-segmented but the basal segment is sometimes so small that they appear 4-segmented (viewed with a hand lens).
Mostly tropical species often associated with decaying wood and preying on the larvae of other insects. Some species are mycophagous (fungivorous). Two species, the cadelle and the Siamese grain beetle (family Lophocateridae of Hinton and Corbett, 1972) are of economic importance in stored products. (Trogositidae previously known as family Ostomatidae in Munro's classification "Pests of stored Products").
(i) Tenebroides mauritanicus (L.). The Cadelle.
Large (5-11 mm) shining-black oblong beetle. Prothorax with base distinctly separated from the base of the elytra. Elytra possessing longitudinal ridges.
The eggs are laid loosely in batches in the substrate or are tucked into crevices and hatch in 7-10 days. The larvae, which are whitish and cylindrical becoming large and fleshy when matured are approximately 18 mm long and easily recognized by the two black horny terminal points and black head and thoracic shield. Feeds on damaged grain when young and later almost exclusively on the germ of the grains while cannibalism and predation are also common. There are four larval instars the last of which searches for a pupation site between the timbers of the store or burrows into the timber hollowing out a chamber within. In temperate regions the cadelle over winters as an adult or larva leaving the grain to shelter in the fabric of the store. The female may produce more than 1000 eggs in a lifespan from 6 to 12 months, but some adults survive for nearly 2 years, making the cadelle one of the longest lived insects that attack stored grain.
The life-cycle may be completed in from 70 days to more than one year. Warm damp grain is preferred.
T. mauritanicus is a cosmopolitan pest whose habit of burrowing into timber structures, sacks and flour-mill silks causes much structural damage as well as providing hiding places for other pests. It is a difficult pest to control by application of insecticides. The lowering of germination caused by both adults and mature larvae feeding on the germ is probably the most appreciable from of grain loss. Both the adults and larvae can survive for long periods without food and often remain hidden in wooden bins for long periods after the grain has been removed. Newly harvested grain becomes infested within a relatively short period.
(ii) Lophocateres pusillus (Klug). The Siamese grain beetle.
Small (2.7-3.2 mm) flattened reddish-brown beetle. Prothorax with base closely attached to the base of the elytra which also possess longitudinal ridges. Both the margins of the thorax and wingcovers are more distinctly flattened.
The eggs are laid in clusters, generally in crevices, and there are four larval instars. The optimum temperature for development is approximately 30°C and can be completed down to 10% R.H. At 70% R.H. development from egg to adult is completed in 49 days at 35°C and 180 days at 20°C.
The Siamese grain beetle is now well established in the southern states of the USA, being commonly found in rice mills in Texas. Its economic significance has not been adequately demonstrated, but it often exists in large numbers on both paddy and milled rice in some Asian countries. Evidence seems to suggest that it is capable of feeding on more than just detritus in bulk grain, especially since the immature larvae are certainly capable of penetrating or utilizing any husk defects that can support populations of S. oryzae and R. dominica.
11. PTINIDAE
Because of their elongate legs and antennae, and stout rounded hairy bodies, they have generally been referred to as spider beetles. The antennae are situated in front of the head between the eyes and are generally close together. They are 11-segmented and never thickened epically. The base of the prothorax has a short and narrow constriction or neck. The elytra completely cover the abdomen and there are either four or five visible abdominal sternites. All tarsi are 5segmented, with segments 1-4 decreasing in length. It is a small family of 500 described species, of which 24 have been found associated with stored food products in various locales throughout the world. Closely related to the Anobiid beetles previously described.
They are a cosmopolitan family, which is well represented in the tropics, but only of economic significance in temperate regions. Generally associated with stored foods as scavengers feeding on dead insects, excrement or dry vegetable matter.
The "hairy spider beetle" Ptinus villiger (Reitter) is a reddish brown beetle marked with four irreguar white patches on the elytra. Approximately 3.5 mm long it is a common pest in the Prairie Provinces of Canada and Northern USA. It attacks stored grain and all types of milled cereal products. The female lays about 40 eggs and under favourable conditions development takes 3-112 months. P. raptor Sturm is an allied species which is as common as the hairy spider beetle in Canada.
The "white-marked spider beetle" Ptinus fur (Linneaus) closely resembles the hairy spider beetle in appearance and habits. It is 2.0-4.3 mm long and feeds on both animal and plant matter and attacks flour, feed, grain and miscellaneous foodstuffs but is rarely abundant enough to inflict serious damage. The brown spider beetle Ptinus clavipes Panzer ( = P. hirtellus Sturm) closely resembles P. fur, is 2.3-3.2 mm long, but can be distinguished from that beetle by the lack of white hairs or scales on the elytra. Ptinus tectus Boieldieu ( = P. ocellus (Brown)) is also close in appearance, is 2.5-4.0 mm long, but the elytra are so densely clothed with brown or golden brown hairs that strial punctures and intervals are not distinct.
The female may lay about 1000 eggs, but 270 would be more typical during a life-span of 5-6 months. Access to water is essential for maximum fecundity.
Optimum temperature for development is between 23-27°C and at 70% R.H., the time from egg to adult is 62 days (or 78 days at 20°C).
The adults cannot fly, and are most active in dark damp slaces. The species is often associated with birds nests and bat roosts which may act as reservoirs for reinfestation. It is a hardy beetle and has a higher rate of increase compared to other Ptinids.
P. tectus is cosmopolitan but of particular importance in temperate regions and is the most destructive of the spider-beetles. All types of cereals, cereal products, oilseed meals, but not oilseeds themselves, are attacked as are many spices and animal products. Adults and larvae readily bore through paper or cardboard containers and sacks particularly through adjacent surfaces, causing the containers to split.
Mezium americanum (Laporte), "the American spider beetle is a small spider beetle with a golden head and thorax and shiny subglobular body that is characteristic of this genus. It is a scavenger generally found in cereals and oilseeds but of relative little importance. It is cosmopolitan compared to M. affine Boleldieu which is restricted to more temperate regions, ever though it is best suited to the tropics (optimum humidity and temperature is 70-80% R.H. and 30-33°C respectively, when development is completed in 62 days; females lay 460 eggs and have a life-span of 17 to 21 months).
A closely related species, the bag beetle, Gibbium psylloides (Czenpinsky) is a small (1.73.2 mm) dark brown shining beetle which is distinguished from M. americanum by the head and thorax, which are densely covered with small scales or scale like hairs.
A cosmopolitan species associated with a variety of produce such as grain residues, cotton seed, linseed, animal fertilizers, dried egg etc. It is most frequent in the tropics and sub-tropics, particularly on the outsides to bags, but it is of little economic consequence. It also is reported as occurring in the extreme southern portion of the USA, whereas M. affine is the common form in the Northern States and Canada. Females survive 10 months during which time she lays some 300 eggs. Optimum conditions are 33°C when development takes 45 days (116 days at 20°C) at 70% R.H. (still possible down to 40% R.H.) and is regarded as cold tolerant.
Other Ptinids that maybe encountered are P. pusillus Sturm, Tipnus unicolor Piller and Mitherpacher, Trigonogenius globulus Solier and Niptus hololeucus Faldermann among others (identification of spider beetles from Hinton, H.E. (1941) "The Ptinidae of economic importance". Bull. Ent. Res. 31:331-381).
MISCELLANEOUS STORED PRODUCT BEETLES
CLERIDAE
The Cleridae or "chequered beetles" comprise rather a large family of 2000 species which are mostly of tropical distribution. They are brightly coloured pubescent insects of moderate size with 11-segmented antennae with the apical segments enlarged to form a distinct club. Elytra generally completely cover the abdomen, and there are five or six visible abdominal sternites. The tarsi are all 5-segmented, with the first and fourth often small and indistinct. They are mostly predaceous beetles feeding on wood borers.
1) Necrobia rufipes (Degeer). The copra or redlegged ham beetle.
Medium sized (4-5 mm) dark blue beetle with red legs.
The eggs are laid in batches of up to 30 in cracks and crevices. There are four larval instars, while the presence of a high protein substrate such as fishmeal greatly enhances development and reduces larval mortalith. The larvae are cannibalistic and predatory particularly attacking the larvae of fungivorous beetles. In the tropics, the females live for up to six months and may produce as many as 3000 eggs. However, if sufficient protein is lacking, both longevity and fecundity are greatly reduced. The adults fly readily.
The speed of development may be completed in as little as 42 days at 30°C and 65-70% R.H. but can be completed at humidities down to 50% R.H.
N. rufipes is widespread in the tropics and will attack oliseeds, copra, dried and salted fish and cured meats such as ham and bacon.
2) Paratillus carus (Newman)
Medium sized (5-7 mm) beetle with red head and thorax and blue elytra with a transverse white stripe.
Occasionally found in stored products but is really a predator of timber borers infesting the structure of the store.
3) Thanoclerus buquetii (Lefebre)
Modium sized (5-7 mm) dark brown beetle.
A prodator of Lasioderma serricome, Sitophilus zeamais, Tribolium castancum and other stored product pests.
NITIDULIDAE
A large family of more than 2,000 species which are extremely variable in form, structure and habits. Many inhabit flowers, others are found in decaying animal and vegetable remains, in fungi and in exuding sap while some larvae are predatory. Those important to stored products are attracted to mouldy grain, cured meats and dried or decaying fruit.
Adults are obovate or oblong beetles with 11segmented antennae terminating epically in a distinct 3segmented club. The elytra are shortened so that two or three abdominal tergites are visible, while there is always five visible abdominal sternites. All tarsi are 5segmented the fourth segment shorter than the rest, while the first three segments are dilated and hairy beneath.
1) Caropohilus dimidiatus (F.), The corn-sap beetle.
Small (2-3.5 mm), oblong shining beetle with short truncate elytra; colour is variable from black to brownish-yellow.
The eggs are laid on or in decaying plant materials such as mouldy grain. The larvae pass through four instars in the soft and mouldy parts of the fruit or residue, while the pupae are generally found in the soil. The females each lay about 1000 eggs over 34 months. The adults fly readily congregating at suitable breeding and oviposition sites.
The life-cycle may be completed in as little as 15 days at 32°C and 49 days at 18°C. Corn sap beetles, which are cosmopolitan, may be found in damp and mouldy grain, peanuts, copra, cotton-seed, maize-cobs in both field and in storage. Often found in ricemills breeding in accumulations of broken rice or swarming and crawling over bags. It is not attracted to clean, dry grain in good condition.
2) Carpophilus hemipterus (L.). Dried-fruit beetle.
Small (2-4 mm) oblong shining black beetle with buff spots on the elytra.
Life-history and biology essentially as for C. dimidiatus.
C. hemipterus is a serious cosmopolitan pest of dried fruits, figs, dates and maize-cobs in the field.
LISTERIDAE
A large family of compact, hard, shining beetles with elbowed and listinctly clubbed antennae. The elytra are truncated leaving the terminal abdominal tergites exposed. They are mostly black or brown beetles but the elytra are sometimes marked with red and a few species ire metallic. Some are carrion feeders while others live beneath bark or in the burrows of wood borers. The larvae are generally carnivorous but of little significance in the control of pest species. One member, Carcinops pumilio (Erichson) a small to medium (1.5-9 mm), broadly oval, shining black beetle is cosmopolitan and common in grain residues and groundnuts.
STAPHYLINIDAE
A very large family of small to moderate sized beetles, usually slender and almost parallel sided and somewhat flattened. The elytra are short covering only the first few segments of the abdomen, but the wings are functional and most species fly readily. The beetles are variable in colour and although many are entirely brown or black red, yellow and blue are common. Staphylinids are common in decaying organic matter, dead animals and fungi, many are predators, a few parasites and others herbivores. The larvae are active and pass through three instars.
Most staphylinids are predators but of little practical value in grain storage and their presence is more indicative of damp, unhygienic conditions favourable to infestations of other insects and mites.
CRYPTOPHAGIDAE
A small family of small (2-3 mm) pale or darkbrown beetles found in mouldy environments and in the nests of ants, bees, birds and small mammals. They frequently occur in small numbers in warehouses and live principally on moulds. Some 25 species of the genus Cryptophagus may be encountered in the storage environment such as Cryptophagus affinis Sturm., a small (1.7-2.3 mm) brown beetle, of wide distribution, often found in grain refuse and dried fruit.
LANGURIIDAE
A large family of small to medium sized oval shaped beetles which are mostly black, with orange or red spots, or metallic blue and scarlet. The adults and larvae of most species are fungus feeders.
1) Pharaxonotha kirschi Reitter. The Mexican grain beetle.
Medium sized (4-4.5 mm), shining, deep brown beetle with rather long antennae with a loose three segmented club. It somewhat resembles the confused flour beetle but is distinguished by its more polished surface and longer antennae. This species is found in maize, wheat, beans and flour, common in Mexico and Guatemala, but it is not known to be established in the U.S. Another Langurlid, Cryptophilus integer (Heer) is a small (2-2.3 mm), shining, darkbrown beetle found in warehouses in Europe and North America.
LATHRIDIIDAE
A small family of very variably shaped beetles 1-3 mm long, usually obovate pale brown to nearly black beetles which are found in mouldy plant and animal materials, in vegetable refuse and under bark and stones. Some 35 species of general such as Corticaria, Coninomus, Enicmus and Holoparamecus are recorded from granaries, mainly as fungus feeders but none are of real economic importance although, at times attaining quite large populations.
The antennae of most common species are 11segmented with a rather compact 2 or 3-segmented club. The sides of the prothorax are explanate or dilated and is depressed along the middle and transversely near the base. The elytra completely cover the abdomen and there are five visible abdominal sternites. All tarsi are 3-segmented. Specific differentiation however, is difficult amongst members of this family (a full account is given by Hinton, H.E. (1941), "The Lathridiidae of Economic Importance", Bull. Ent. Res., 32:191-247).
1) Corticaria pubescens (Gyllenhai)
Small (2.3-3 mm), stout, convex reddish-brown beetle, the largest member of this genus which is cosmopolitan in distribution and often found in grain residues in buildings and the field. Corticaria adelaide Blackburn and C. australis Blackburn have been found in standing wheat crops in New South Wales in 1966 (Greening, 1978) but do not pose any threat after harvest where the adults are usually found dead.
MYCETOPHAGIDAE
A small family of small (1.5-5.0 mm), oblong to oval, flattened, densely pubescent beetles which are generally brown to black in colour with yellow or reddish spots on the elytra. The larvae and adults are fungus feeders occuring under bark in haystacks, on mouldy grain and in vegetable refuse. The family is of little economic importance. The antennae are 11segmented with a 2 to 5-segmented club. The elytra completely cover the abdomen and all tarsi are 4segmented except the front tarsi of the males which are 3-segmented.
1) Litargus balteatus LeConte
Small (1.7-1.9 mm), convex, oval shaped, dark brown, hairy beetle with several lighter patches on the elytra. A cosmopolitan species frequently infesting damp spillage or in harvester residues.
2) Typhaea stercorea (L.). The hairy fungus beetle.
Small (2.2-3.0 mm), convex, oval shaped, hairy brown beetle which is common in a wide range of mouldy cereals, groundnuts, tobacco, cocoa, haystacks and in mills, rail cars and domestic premises.
It is also frequently found in cornfields where it is apparently attracted to the decaying kernels on exposed ears. After the corn is harvested and shelled, it is often heavily infested, but there is little feeding on undamaged grain. It rather closely resembles the drugstore beetle, Stegobium panecium (L.) but can be distinguished by the shape of the antennae, which are clavate instead of irregularly serrate.
Another funivorous Tenebrionid, Alphitophagus bifasciatus (Say), is cosmopolitan and frequently found around mills and warehouses where waste materials are allowed to accumulate, and in wet and damaged grain in the holds of ships. It is a small (2.5-3 mm) handsome elongate-oval beetle, which is reddishbrown with two transverse black bands near the apex and base of the slytra. Its biology is relatively unknown, but development is completed in round 30 days at 25°C and 70% R.H., the larvae being reared in moist cornmeal and in spoiled cereals. It is of little economic significance, except like most fungus feeders, it is an indicator of damp and mould grain that is deteriorating and likely to be heavily infested by the more important grain feeders.