Bakers Journal

Knowing What’s in Storage

December 3, 2007
By Zia Siddiqi Ph.D. B.C.E.

Inspection, monitoring and sanitation can help bakeries battle stored-product pests.

32They may be small, but stored-product pests can cause serious damage to baking supplies, food products and bottom lines. Fortunately, a proactive program that emphasizes ongoing inspection, monitoring and sanitation can make a huge difference.

Stored-product pests are a constant threat in bakery settings since they feed off flour, grain and bran, among other ingredients. Most often, stored-product pest infestations originate on the farm and then proceed with the product to processing plants, storage facilities and retail locations. These small pests – measuring between 0.32 and 1.59 centimetres in size – can cause big headaches if they are not properly controlled. 

Though stored-product pests do not pose a health threat, per se, they can cause other problems. Flour, or grain, beetles secrete uric acid, which can negatively affect the flavour of many bakery products. The insects also can cause allergic reactions, and ingestion of certain pests can be dangerous to small children.

Stored-product pests fall into three categories: internal feeders, which feed on the kernel of the grain; external feeders, which feed on the exterior of the product; and scavengers, which feed on the grain after the shell breaks. As with any pest, proper treatment depends upon the accurate identification of the pest in question.

To defend against stored-product pests, managers should consider the following steps as part of an ongoing integrated pest management (IPM) program:

• Inspect all incoming shipments. Keep a product sample from each shipment in a closed jar and monitor it for the tiny larvae that are hard to see with the naked eye or for pests, which will develop if eggs are present. If insects appear in one of the jars, the problem can be traced back to the corresponding supplier.

• Clean up product spills immediately so food debris does not accumulate in cracks and crevices, providing a haven for pests. All baking and food preparation areas must be vacuumed or washed frequently according to a master sanitation schedule.

• Implement a pheromone monitoring system. Pheromones are the chemical secretions of insects used for sex or aggregation and can be used to detect their presence by luring them into sticky traps. Pheromone traps should be placed in a grid configuration, with the distance between each trap determined by the type of pest and its pheromone type. As the traps collect insects, they help localize the source of the infestation so the infested product can be removed from the facility.

• Set a threshold level past which pest control action must be taken. For example, if a customer has a threshold level of five moths, six moths would result in further inspection and investigation and ultimately may involve disposal of the product and a reevaluation of the current pest management program. Certain stored-product pests are more likely to be found in specific products. Both Agriculture and Agri-Food Canada, as well as the FDA in the United States, have established limits for parts/fragments of these insects. These levels are called “defect action levels.” Defect action levels for stored-product pests are low, but not as low as the tolerance levels for other pests, since stored-product pests do not carry disease. More harmful pests can have a zero-tolerance level. 

• Use temperature to freeze or overheat unwanted pests. Stored-product pests will not be active at temperatures under 15°C. Of course, managers must first consider the effect of this control strategy on the product itself.

• Include the use of insect growth regulators if necessary. These biochemical products interfere with insect development, crippling their reproductive capabilities. As with pheromone traps, proper identification of the pest is a must, as these techniques will not affect non-target organisms.

• Consult a professional if more action is needed. Pest management professionals can review a facility and implement a treatment program that alleviates the infestation with minimal risk to the product and the environment.
Stored-product pest infestations cause serious economic losses within the baking industry every year. By taking a few small steps like monitoring products and inspecting incoming shipments, bakeries can make a big impact on stored-product pests and their bottom lines.

Dr. Zia Siddiqi is quality assurance director for Orkin, Inc. A board-certified entomologist whose career spans more than three decades and several continents, Dr. Siddiqi is an acknowledged leader in the field of pest management in Canada and the United States. Contact Dr. Siddiqi at or visit to learn more.

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