Insecticide-treated film wrap to protect small packages from infestation [Insect control]

Polymer films treated with permethrin or with chlorpyrifos-methyl were heat-shrunk around bundles of small bags containing cornmeal. The wraps treated with chlorpyrifos-methyl were either completely sealed or had open ends, while permethrin-treated wraps were completely sealed. During 12 months of exposure to large, mixed populations of stored-product insects, sealed wraps containing 203 mg/m super(2) of permethrin or 1,318 mg/m super(2) of chlorpyrifos-methyl significantly reduced the incidence of infestation. Sealed wraps containing 12 mg/m super(2) of permethrin or 377 mg/m super(2) of chlorpyrifos-methyl failed to provide adequate protection from infestation, as did sealed, untreated film wraps. Most of the bags in open-end bundles made of chlorpyrifos-methyl-treated film were infested at each periodic examination.