Exercise caution if there are still honey bees in the area, especially if you are allergic to bee stings. If the bees are still congregating around the horse feed, you may need to wait until dark when they should return to the hive for the night.
Mix two parts orange oil to one part water and pour it into a spray bottle. Use a clean spray bottle, not one that has been previously used for fly repellent or other things around the barn. The smell of the orange oil helps to deter honey bees, wasps and other stinging insects.
Close the lid on the horse feed container and spray the top and sides with the orange oil mixture. Allow the mixture to soak into the wood and permeate the surfaces.
Keep the lid tight on the horse feed container. If the lid is not tight, the bees will be attracted by the smell, even with the orange oil sprayed around the perimeter. A loose or ill-fitting lid is also an invitation to mice and other rodents. Invest in a solid storage container for your horse feed or simply use a plastic garbage can with a properly fitted lid.