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Stored Product Insects


There are a wide variety of Stored Product Insects which can become a problem both for domestic and commercial customers.

Please find below some of the more common varieties:




Red Flour Beetle/Confused Flour Beetle 
 (Tribolium castaneum/Tribolium confusum)

Occurrence:

Found throughout the world on a variety of products the Red Flour Beetle is more common in warmer climates than the Confused Flour Beetle.

Minimum Life Cycle: 20 days.


Biology:

Red Flour Beetle (Tribolium casteneum)
Eggs: approximately 450 per female over several months, laid on food stuffs.

Larvae: these prefer cereal embryos.

Adults: 3.5mm in length, can live for 18 months, some strains can be resistant to some insecticides.



(Images: Top-Red Flour Beetle, Bottom-Confused Flour Beetle)



Grain Weevil (Sitophilus granarius)

Occurrence:

Temperate zones, attacks cereal grains.

Minimum Lifecycle: 4 weeks

Biology:

Eggs: up to 200 per female laid within grains

Larvae: live within the grains, can survive for 10 weeks at 5c.

Adults: 3.5mm in length, cannot fly, can easily survive UK winter in unheated buildings.



Rice Weevil (Sitophilus oryzae)

Occurrence:

Both tropical and temerate zones, found on cereal grains.

Minimum Lifecycle: 4 weeks

Biology:

Eggs: up to 200 per female in stored cereal grains and by flying adults in grains in the field. 

Larvae: feed on the grain.

Adults: 2.5mm in length, also feed on the grain, cannot normally survive a winter in temperate climate without heat.



Tobacco Beetle (Lasioderma serricorne)

Occurrence:

Worldwide, primarily found on tobacco but can be on other products.

Minimum Lifecycle: 19 days

Biology:

Eggs: approximately 100 per female laid on produce.

Larvae: these are responsible for the damage as they feed on the product. Developemtn time is dependent on food availability.

Pupae:  these form within the produce.

Adults:  3mm in length, do not feed, they can live for 2 - 4 weeks.



Lesser Grain Borer (Rhizoperha dominica)

Occurrence:

Throughout the world, both in cereal and coarse grains.

Minimum Lifecycle: 25 days.

Biology:

Eggs: up to 500 per female.

Larvae: voracious feeders, eat into grains and also feed on grain dust.

Pupae: these usually form within the grain.

Adults: 3mm long, also are voracious feeders and are long lived.



Larger Grain Borer (Prostephanus truncatus)

Occurrence:

Americas and now Africa, maize growing areas.

Minimum Lifecycle: 25 days.

Biology:

Eggs: up to 600 per female laid among grain.

Larvae: feed on maize.

Adults: 4mm in length, can fly, will also attack other foodstuffs.



Rust Red Grain Beetle (Cryptolestes ferrugineus)

Occurrence:

Worldwide, normally secondary pests but will also attack damaged grains.

Minimum Lifecycle: 23 days.

Biology:

Eggs: laid in produce, often in splits or cracks in grain.

Larvae: feed on or near the endosperm of the grain.

Adults: 2mm ling, also feed and can live 6 - 9 months.



Saw-toothed Grain Beetle (Oryzaephilus surinamensis)

Occurrence:

Worldwide, important pest of many stored products and a secondary pest of whole grain.

Minimum Lifecycle: 20 - 25 days.

Biology:

Eggs: up to 400 per female laid in the grain.

Larvae: develop  quickly, particularly where there is high moisture content.

Adults: 3.5mm long, can be long-lived up to about 3 years.



Merchant Grain Beetle (Oryzaephilus mercator)

Occurrence:

Worldwide, as above an important pest species of stored products.

Minimum Lifecycle: 20 - 25 days.

Biology:

Eggs: up to 400 per female.

Larvae: as above, develop rapidly at high humidity.

Adults: 3.5mm in length, can live for up to 3 years.



Khapra Beetle (Trogoderma granarium)

Occurrence:

The most important stored product pest for grain importers and exporters, these primarily attack grain and oil seeds.

Minimum Lifecycle: 25 days to 4 years in diapause (lying dormant).

Biology:

Eggs: up to 80 per female.

Larvae: may enter diapause under unfavourable conditions when it becomes difficult to treat.

Pupae: in crack and crevices.

Adults: 3mm long, short-lived do not feed or fly.



Dried Bean Beetle (Acanthoscelides obtectus

Occurrence:

Worldwide on pulses both before harvest in the field and when stored.

Minimum Lifecycle: 3-4 months.

Biology:

Eggs: laid in pods before harvest and among stored seeds.

Larvae: enter and feed within one seed.

Pupae: form within the seed.

Adults:  3.5mm in length, non-feeding and short lived. 



Flour, Grain or Cheese Mites (Acarus siro)

Occurrence:

Throughout the world, will attack many types of produce especially if moisture content high or have been attacked by fungus.

Minimum Lifecycle: 17 days.

Biology:

Eggs: minimum 100 per female, egg stage can survive at 0 degrees for months.

Immature Stages & Adults: attack cereal embryos, dormant stage resists starvation, chemical treatments and dessiccartion.



Mill Moth (Ephestia kuhniella)

Occurrence:

Temperate areas, attacks cereal products especially flour.

Minimum Lifecycle: 6 - 9 months

Biology:

Eggs: laid on or near to produce.

Larvae: like flour dust, webbing from heavy infestations can clog machinery.

Pupae: form in the produce from overwintered larvae.

Adults: 21mm long, do not feed and are short lived.




Warehouse, Cocoa or Tobacco Moth (Ephestia elutella)

Occurrence:

Temperate areas, a serious pest which attacks many raw and processed products.

Minimum Lifecycle: 6 -9 months.

Biology:

Eggs: laid near or on produce.

Larvae: move to and over produce feeding and spinning threads which can form webs.

Pupae: form in cracks.

Adults: 16mm in length, do not feed, short-lived and fly at dawn and dusk.



Tropical Warehouse Moth (Ephestia cautella)

Occurrence:

Tropical areas, attacks a wide variety of products.

Minimum Lifecycle: 25 days.

Biology:

Eggs: up to 300 per female on or near produce.

Larvae: move to and over produce spinning threads, particularly thickly prior to pupating.

Pupae: these form near to produce.

Adults: about 16mm long, these are non-feeding and short lived. they tend to fly around dusk and dawn.




Indian Meal Moth (Plodia interpunctella)

Occurrence:

Worldwide in cereals, ground nuts and dried fruit.

Minimum Lifecycle: 26 days

Biology:

Eggs: laid near produce up to about 300 per female.

Larvae: spin threads as they feed, when in the pre-pupal diapause they can be difficult to treat with insecticide.

Pupae: these form in produce.

Adults: approximately 16 mm in length, short lived and do not feed.



Angoumois Grain Moth (Sitotroga cerealella)

Occurrence:

In tropical grains, for example maize, and sorghum. They commonly attack prior to harvest.

Minimum Lifecycle: 4 weeks

Biology:

Eggs: these are laid on the surface of the grain.

Larvae: they bore into the grain and remain there until pupation.

Pupae: these also form within the grain.

Adults: about 16mm long, these do not feed and are short lived.