In recognizing that insects can develop resistance to insecticides, especially if the same chemical class is used repeatedly, the Province of Manitoba suggests that alternative control methods be used to help minimize the development of resistance. Food Grade Diatomaceous Earth is suggested for use in the cracks and crevices of buildings, empty bins and storage containers as well as a product that can be used for direct application to grain. While it is important to follow the directions on the label of the approved product (approved product labels can be found on Health Canada’s Pest Management Regulatory Agency (PMRA) website), the Canadian Grain Commission suggests that diatomaceous earth is most effective as a residual insecticide when applied directly to dry grain as it is being moved into bins during harvest. Maximum effectiveness is ensured when the grain is treated for six weeks at a temperature above 20°C.
It must be noted that diatomaceous earth can reduce test weight. As well, flow rates should be decreased when diatomaceous earth has been applied, as the product will increase grain friction.