Stored Product Insects

We’ve been carrying out a number of pest control jobs concerning stored product insects recently and I thought it would be useful to explain what Stored Product Insects are, how we control them and tips for preventing infestation.

Stored product insect (SPI) is an umbrella term for any insect or mite that infests our stored products such as cereals, flour, nuts, dried fruit, dog food, fish food etc.  The vast majority of SPI’s are species of beetles, weevils and moths that take advantage of our stored food products. They cause problems in kitchens, pantries, warehouses, bakeries and food production sites, in fact anywhere that dried food is processed or stored.

We have recently treated a domestic property for an infestation of biscuit beetle. These are small brown beetles that are about 2-3mm long and oval in shape. As with all beetles they have a complete life cycle, where there is a distinctive egg, larva, pupa and adult stage.  They will infest most cereal based products and in this case had taken a liking to a packet of ryvitas that had been opened for a number of months and left at the back of a kitchen cupboard. Biscuit beetles had honed in on this and decided to set up home resulting in hundreds of beetles infesting most of the kitchen cupboards. The ryvitas were peppered with tiny holes, where the adults had emerged from pupal cases within the ryvita.  All of the cereals and stored food that was not in sealed containers had to be disposed of, all the kitchen units including behind the plinths had to be checked and thoroughly cleaned to remove all food residues. An insecticidal treatment then had to be undertaken to eradicate all stages of the life cycle.

As is shown in this example, SPI’s are typically quite small and complete most of their life cycle within their food source. This means that heavy infestations can develop before they are noticed. They can spread the infestation to other foodstuffs compounding the problem. Some of the adults are active flyers, enabling them to infest products that are spacially separated.

Another SPI that we recently treated was an indian meal moth infestation in a restaurant. These moths are 8-10mm long, have a distinctive wing colour in that the first third of the forewing near the head is a creamy colour and the rest of the forewing is a copper colour. The life cycle of all moths is complete as in the beetle life cycle and it is the larvae that cause the damage and contamination of the products. The larvae spin silk within the food, which is combined with droppings and food debris that is known as frass and this renders food products unusable.  In this case the cause of the infestation was nuts that had spilled to the rear of the shelves in the food store. The moths had then spread to other stored cereals necessitating disposal of large amounts of raw materials. The food store was meticulously cleaned and an insecticidal treatment carried out to ensure all stages of the life cycle were eradicated. This moth can enter a larval resting period known as diapause that enables them to survive cooler conditions. It was therefore essential that a long term monitoring programme was initiated using pheromone traps that mimics the pheromone emitted by female moths. This ensures early detection of any future infestation.

These are just a couple example of SPI’s of which there are many more. There are some simple steps that homeowners and businesses can take to prevent SPI infestation:

• Check all stored food products before they are stored and dispose of any that are found to be infested.
• All food products should be stored in sealable containers.
• Ensure that good stock rotation procedures are in place – first in first out.
• Routine, thorough cleaning of storage areas.
• Routine monitoring to identify the early signs of an infestation.

At Kestrel Pest Management we offer our professional a professional SPI treatment service that will ensure your homes and businesses remain free of SPI’s.