Beetles
There are several beetles that cause damage to foodstuffs and manufactured products. The injurious stage is often the larvae which through its consuming habit and waste deposits scan spoil products, packaging and structural materials. The following is a short list of main pest that can be encountered.
Mealworm Beetle (Tenebrio molitor)
This insect is often associated with birds' nests, and long standing food residues or other debris in storage situations. As it is quite capable of flight, infestation may not necessarily be localised. Females lay up to 500 eggs over a period of weeks. Emergence of larvae will occur after around 2 weeks when they begin to feed immediately on any suitable foodstuff in the vicinity. Larvae may pass through 10 - 20 instars over 1 - 1 ½ years before pupating. Adult forms emerge 3 - 4 weeks later.
Although large numbers of this pest species are seldom encountered, its presence may be cause for concern in food handling and storage situations. It is not a primary storage pest, and as such its presence may indicate the need for increased attention to hygiene and maintenance.
Tobacco / Cigarette Beetle (Lasioderma serricorne)
Primary pest of leaf tobacco, cigars and cigarettes, although this insect will infest a good many other stored food products also. Widely distributed in the tropics, although infestations in the temperate zones are susceptible to cold conditions. Complete metamorphosis life cycle. This species is closely related to woodworm and Biscuit / Drugstore Beetle, all being members of the family Anobiidae. Feeds also on dried vegetable materials including cereals spices and cocoa beans. Ready fliers with relatively high breeding potential.
Primary pest of tobacco. This pest causes a large degree of economic loss, particularly (although not exclusively) to the Tobacco industry. It is one of the few species of insects that does not find nicotine repellent. Larvae are able to fly and chew through many types of packaging.
Biscuit Beetle (Stegobium paniceum)
World-wide distribution with a preference for temperate climates. Cosmopolitan in choice of habitat, infesting all manner of commodities in both commercial and domestic food stores. Life cycle may be completed inside the food commodity. High potential for cross infestation due to ability to fly. Complete metamorphosis life cycle. Larvae are voracious feeders, quite able to chew through almost all forms of packaging. Humidity limits of 10% and 70% define limiting factors. Closely related to Woodworm and Tobacco / Cigarette Beetles (Anobiidae) which it closely resembles. Only able to complete one life cycle per year below optimum conditions.
May attack not only foodstuffs but leather, hide, paper and other manufactured goods. Documented as able to eat through almost all packaging including metal. Wide distribution, ability to fly and omnivorous nature make this species a significant commercial and domestic pest. Monitoring strategies may be used to increase control efficiency.
Rust Red Grain Beetle (Cryptolestes ferrugineus)
Distributed globally, this species is commonly found in grain storage situations. Their relatively high minimum breeding temperature of 18 to 22°c reflects their sub tropical origin. 40 - 50% RH is required for development. Eggs are laid singly within the foodstuff, adhering to it. Larvae attack food immediately on emergence, moving through approximately 4 moults before pupation that takes place in the food commodity. Adults emerge, mate and continue the cycle, which under optimum conditions may be completed within 20 days. In suitable conditions of high temperature, adults may fly.
Often occurring in conjunction with other primary grain pests such as weevils and saw tooth grain beetles, it is associated with high temperature and humidity caused by other infestations. Prevalent in the hot conditions of late summer, populations can grow to large numbers. Will also infest dried fruit and oil seed but is more usually found in cereal products.
Flour Beetles (Tribolium Spp.)
World-wide distribution for both species. Almost always associated with stored food commodities including animal feeds and flour. Populations are established in ships holds, storage silos, flour mills, bakeries and pantries around the globe. Microhabitats in large industrial situations include machines and process equipment where build up of old food substrates allow completion of life cycle.
Complete metamorphosis life cycle. Females lay up to 450 eggs over their lives, which may be as long as 18 months depending upon conditions. Life cycle may be completed in 7 weeks at 25°C but in warmer conditions such as those in bakeries, this may be reduced to 3 weeks. This high breeding potential can lead to very large infestations in suitable conditions.
A highly significant, widely distributed and successful primary pest in the milling industry. Although it will infest stored grain, it tends to be as a secondary pest that prefers to colonise materials already attacked by primary grain pests. Economic loss due to this insect alone is high, due to it's tendency to taint food substrates with secretions.
Sawtooth Grain Beetle (Oryzaephilus surenamensis)
Wide tropical and temperate distribution. One of the principal pests of bulk stored grain. Relatively cold hardy, although minimum breeding temperature is 16 - 17°C. In warm climates, this species exists outdoors, feeding on acorns and seeds. Mated female may lay between 100 and 400 eggs over a period of 6 - 10 weeks. Larvae attack broken or damaged grains, usually starting with the germ. Progression from egg to adult can be completed in 20 days under optimum conditions, although 3 months is more usual.
As one of the main pests of bulk grain storage, O. surinamensis is one of the principle SPI pests. It has an extraordinarily high breeding potential which is linked to the ability of infestations to increase the temperature of their micro-habitat. This may lead to sprouting, charring and large scale economic loss.
Larder Beetle (Dermestes lardarius)
Widespread throughout Europe, hide beetles all require a diet which is high in protein. Occurring naturally in bird's nests, this group of insects is well adapted to infesting intensive poultry units, and is one of the main pests of such areas. Adult females lay between 200 to 800 eggs that hatch within around 1 week. After a number of moults, larvae leave the food source in search of a suitable site for pupation. Such sites include wooden panels and structural timber that the larvae may burrow into. Total life cycle may be completed in 8 - 12 weeks.
A serious pest of kitchens, poultry houses and occasionally, piggeries. Feeding on and breeding in proximity to food scraps, the presence of hide beetles may indicate poor hygiene.
Woodworm / Furniture Beetle (Anobium punctatum)
Widely distributed in temperate climates. Commonly found in the outdoor environment where it is part of the natural decay of organic materials. Indoors, it may infest almost all timbers including structural and ornamental. Adults emerge from timber in the spring and early summer. Eggs are laid into crevices immediately after mating, Sawn ends of manufactured timber is an example of a typical oviposition site. Females lay around 30 eggs in small groups. Emergence will occur 2 - 4 weeks later, when the young larvae will bore into the timber. Full life cycle indoors takes between 2 and 4 years. Final instar larvae will tunnel toward the surface and construct a pupation chamber near to the surface. Adults emerge, completing the cycle, leaving a characteristic bore hole and gritty powder in the vicinity of the hole.
A serious and significant pest of structural and ornamental timber. Adult forms may enter premises through roof eaves and lofts during the spring. Long term infestation may threaten even substantial structural timbers.
Carpet Beetle (Anthrenus Spp.)
While being sub-tropical in origin this pest is widely found in Europe. Often found in and around foodstuffs, and occasionally in grain. May also be seen wandering on walls and windows as well as on carpets. Bird's nests, animal remains and dead insects are focal points for populations that thrive on the source of protein. Mating occurs immediately subsequent to emergence. Females produce between 20 and 100 cream coloured eggs that are approximately 0.5mm in length, with spines at one end. Hatch will occur within 2 - 4 weeks, whereupon the characteristic "wooly bears" move through a number of instars before reaching adulthood. Pupation lasts 10 - 30 days. Adults are capable of flight.
Larval forms cause significant damage to keratin containing products such as wool, fur, leather, silk and dried animal remains. Although this pest creates no webbing, its activities are indicated by the presence of clean, irregular holes in textiles in the vicinity. Quantities of larval skins or exuvia will also indicate presence of this pest.
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