Stored product insects: The world’s most expensive pests


Stored Product Insects (SPIs) are a physical risk to businesses which operate within the food industry such as food processors and food retail companies. They are regarded as the most expensive pests where a single infestation from a SPI can result in increased expenditure for businesses, reduced profit, negative brand attention, and major audit non-conformance.

These pests tend to live in the product itself, as well as food processing equipment and in the product storage. Finding them can prove extremely difficult. To add to this complexity they are small in size and share a love of confined spaces.

Stored product insects come in both the crawling and flying variety of insects. They commonly belong to the insect orders Coleoptera (beetles and weevils), Lepidoptera (moths), Psocoptera (booklice) and the Arachnida order, Acarina (mites). They can often be found infesting food ingredients during the delivery to a food retail store or in raw food ingredients when storedLarder Beetle for a long time. Items such as cereals, nuts, spices and preserved meats, to name a few, are at particular risk. SPIs can also cause damages to packaging, making some food products susceptible to accumulating food-borne diseases, whilst also reducing their shelf life.

Growing infestations

A stored product insect’s ability to damage food products and packaging can be a result of its breeding habit. Some stored product pests can quickly develop into large populations, with some females laying up to 400 eggs in a lifetime. Both the adult’s and the larvae’s diet consist of the food products they infest, which can have a large impact on stock. Their breeding habits are a risk in itself when SPIs lay their eggs in a food source. When the eggs hatch, the larvae will consume the food products by burrowing into the food materials and consuming it from the inside out. It is important to be able to identify the earliest signs of a problem to enable a quick solution and a guaranteed control measure which prevents a re-infestation.

Indian Meal Moth

Light sources

Food beetles are attracted to light sources. Areas, where food products are stored, are often well lit, which aids in the attraction of stored product insects. It is more common to find a stored product pest infestation in a well-lit area than it is to find one where there is little to no sources of light.

Stock loss

On top of the damages stored product pests can cause to food products via their feeding, and breeding habits, they can also contaminate food materials with their waste, tainting the goods they are infesting.

This will increase the need to reject and waste products, having an effect on stock and replacement costs.



The small size of stored product insects allows them to successfully inhabit and infest businesses handling food. The saw-toothed grain beetle’s small size allows it to easily hide in crevices, making detection difficult to the untrained eye, whilst also allowing it to penetrate packaged food products.

Integrated Pest Management

The most effective solutions for businesses to protect themselves from stored product insects and other pests is to implement an Integrated Pest Management program.

Rentokil’s approach combines four core principles:

  1. Exclusion: Eliminating the opportunities for entry
  2. Restriction: Training staff in pest awareness to spot the early signs of conditions that favour the development of pest infestations.
  3. Destruction: Utilising innovative solutions to remove pests from premises
  4. Monitoring: Regular checks and monitoring devices to detect early warning signs of pest infestations

Contact the experts at Rentokil for support in controling stored product insects in your food business.



  1. Stored product insects are common at my kitchen especially when I store grains. Despite storing them in air tight containers there is the infestation. Could you help me with effective tips to get rid of them?

  2. Thanks for sharing this article. I agree with what you said. I think that it is better to check the products regularly. I think that by doing this we can avoid a bigger pest damage.

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