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 Red Lake Diatomaceous Earth 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).