Stored Product Infestations (SPI) are usually as a result of one of a few insects in the UK. At the bottom of the page we have details of the more commonly found SPI with general information on their biology and habits.
There are a few dozen species of beetles, moths and mites that commonly infest dried and processed plant and animal products.
The materials that these insects breed in is extensive, some of the more common products include; grain of any type, pasta products, flour, nuts, spices, drugs (including marijuana), dried meat, dried dog food, tobacco, decorative corn, dried flowers, breakfast cereals, candy bars and energy bars.
These insects are always present in the environment and will attack any of these products given time, so if any of these products remain unprotected on the shelf in a super market, home, warehouse or any other situation for an extended period of time they will become infested. The length of time before an infestation occurs is dependent upon the particular environment.
An infested packet of pasta in a kitchen cabinet may have become infested within the cabinet if its been there for some period of time (usually more than 12 months) or it may have become infested on its journey to your cabinet, be it at the origin of manufacture, during one of its many stages of travel, during storage in a warehouse or at the grocery store or supermarket.
Larvae and adult forms of stored product pests can penetrate most types of packaging, foil, plastic or cardboard, but they can not penetrate canned food, glass jars or more resistant plastics.
These stored product pests have a few characteristics in common;
- they are small – adults are 3 to 6mm in length or even smaller in the case of mites.
- the early immature stages (eggs and early instar larvae) are nearly microscopic in size which makes early detection of an infestation difficult.
- the majority of these stored product insects lay several hundred eggs per female
- most have a short life cycle, usually no longer than a few weeks from egg to adult, – allowing for the development of large infestations over short time periods
To gain successful control of stored product infestations it is necessary to identify the pest insect and determine the extent of the infestation.
A good visual sign of an infestation is the observation of small moths or beetles in the vicinity of stored products, in which case a thorough inspection of all product should be carried out.
Usually when these insects reach the pupal stage (post larvae, pre imago (last stage of development)) they will move away from the site of their origination eating thru any packaging that may be acting as a barrier, resulting in emergence holes on the outside of product packets.
An inspection of the product may reveal webbing (produced by some of the moth larvae), frass (a mix of faeces and body debris) and various stages of larvae feeding and damaged product.
All product within an area of infestation needs to be thoroughly inspected and ideally isolated to see if further damage occurs over time (initial stages of infestation may be too small to identify and will require time for them to develop so that they can be seen visually).
Any products infested should be discarded or destroyed, in the case of small infestations within the home the remaining product can be treated using heat, stored product insects cannot survive in temperatures above 40 C (100 F) for an extended period of time. A few minutes in the microwave can also be very effective.
Insects are far more tolerant of low temperatures, and freezing may not be as effective a treatment.
in larger scale infestations fumigation is often the only viable treatment.
Often these pests leave the infested product and pupate in nearby areas, so all shelving, racks and other storage areas with product should be thoroughly cleaned and possibly sprayed with an insecticide that carries a food safe label.
Biscuit, Tobacco & Common Furniture Beetles
Found in shops and domestic larders, infesting a wide variety of dried vegetable matter, cereal products, flour, bread, breakfast cereals, spices, beverage concentrates and drugs.
Carpet, Furniture, Varied Carpet & Museum Beetle : Anthrenus spp.
The Furniture and Varied carpet beetles (“wooly bears”) are pests of animal products (and occasionally food products of plant origin).
The Museum beetle is a pest of dried specimens, it also attacks textiles and has been recorded as infesting grain.
The Fur beetle is found in products including furs, skins, textiles and grain.
Carpet beetles are a major pest of textiles.
Confused Flour Beetle, Rust-Red Flour Beetle, Dark Flour Beetle, Small-Eyed Flour Beetle, Long-Headed Flour Beetle, Broad-Horned Flour Beetle, Slender-Horned Flour Beetle.
Usually found in bakeries and flour mills, serious pests of cereal products, grain, flour, porridge oats and rice bran. Other products that may be infested are oil seed, oil cake, nuts, dried fruit, spices, chocolate, bones and other animal products.
Saw-Toothed Grain, Merchant Grain & Foreign Grain Beetle : Oryzaephilus spp.
Infest cereals and a wide range of foodstuffs. Retail premises and warehouses can suffer infestations and the beetles frequently appear in packaged food.
Grain Weevil, Rice Weevil & Maize Weevils : Sitophilus spp.
Grain weevils are major pests of farm-stored grain, they will also attack other hard cereal products, macaroni and spaghetti. Fine cereal products are unsuitable for breeding purposes unless they become caked.
Larder Beetle, Bacon Beetle, Hide Beetle, Leather Beetle : Dermestes spp.
Dermestes beetles eat animal products; hide, skin, bone, dried meat, fish meal and dog biscuit. Infestations in domestic premises are often found in larders or may be found feeding on dead rodents or birds concealed somewhere.
Lesser Grain Borer
Is associated with a wide variety of vegetable materials, wheat, barley, maize, rice, dried potatoes, dried herbs and biscuits, and have been recorded in wood and books.
They are a serious pest of grains in Australia and India and infestations can be found in grain stores, ships holds, flour mills and animal feed mills.
Australian Spider Beetle, White-Marked Spider Beetle, Golden Spider Beetle, Hump Spider Beetle.
Spider beetle larvae will infest all dry animal and vegetable matter including grain, spices, fish meal, dog biscuits, dried fruit and a wide variety of miscellaneous debris.
As well as boring holes they contaminate commodities with droppings and silk webbing.
Stored Product Moths
Warehouse Moth (Cacao Moth, Tobacco Moth), Tropical Warehouse Moth (Dried Currant Moth), Mediterranean Flour Moth (Mill Moth/Flour Moth), Indian Meal Moth (Dried Fruit Moth), Rice Moth, Brown House Moth, White-Shouldered House Moth, Common Clothes Moth.
Moths can be found in a variety of stored products, some species are associated with goods of vegetable origin while others are associated with animal products – particularly textiles.
Considerable damage is done by larvae to stored goods both by feeding and by contamination with webbing and frass (their waste product).
Common name for the Common Furniture Beetle