Level the top of the grain bin without compressing the feed corn. Apply an approved grain protectant such as Bacillius thuringiensis, pyrethrin or plain diatomaceous earth to the top layer of corn according to package directions. Coat the top of the corn completely to eliminate and prevent top-feeding insects.
Suspend dichlorvos-impregnated strips in the open spaces above the grain from spring to fall. Use one strip per 1,000 square feet of air space to catch moths before they can lay eggs in the feed corn.
Seal the grain bin as tightly as possible before attempting fumigation, since maximum gas retention is vital to success. Use phosphine tablets according to the package directions, being sure to allow for empty head space. Insert tablets with a probe, applying tablets at 12-inch intervals, with the last tablet 6 inches below the surface of the corn. Divide the bin mentally into quarters and apply tablets to the most-difficult-to-reach corner first, moving toward the easiest corner. Insert tablets beginning at the bottom and work your way toward the top.