Diatomaceous earth works well to eliminate many crawling insects including darkling beetles.
The following guidelines will help you to achieve the best results when applying DE-CIDE, a food grade diatomaceous earth product to your barn or poultry house.
Apply the diatomaceous earth to a clean surface (if possible).
Start at one end of the barn or poultry house and apply the diatomaceous earth extending 4 ft out from the wall around the entire perimeter.
Apply a thick layer of DE in the first 2 ft out from the wall and a thinner layer for the following 2 ft. (one 40 lb bag will take you 25-35 ft.)
Be sure to use a fine granulation (or a powdered granulation, if necessary).
The thicker the application of diatomaceous earth, the more effective it will be (a larger infestation will require a thicker application).