If storing large containers:

* Get air tight containers. Plastic containers encourage more condensation inside than metal. Drier is better; use enamel lined metal if you can.
* CO2 / dry ice treatment. Removes oxygen the critters need to live. Using heavy gloves, place several ounces of dry ice in the bottom of the container, slowly pour the grain on top of it. Do NOT use larger amounts of dry ice. Let stand covered, BUT NOT SEALED without disturbing for 12 hours. The air in the can is driven out by the CO2 gas which fills the container from the bottom. After 12 hours, seal the container, but check every 12 hours for any signs of pressure. If the CO2 continues to dissolve, it can push the top off or blow out the sides! Vent any excess pressure, then reseal the container.
* Silica gel treatment. Keeps the grain too dry to support bug life. Get the 40 gram tins, keep in an airtight container, change every 4-6 weeks, silica gel can be redried in a slow oven.
* Diatomaceous earth (DE). This is NOT the stuff people put in swimming pool filters. Edible diatomaceous earth is a natural combination of silica and trace minerals which has not been heat treated and is available from survivalists via the internet. It acts by drying out insects and eggs so they die. It is not poisonous, or can be washed off whole grains. Don't breath the dust, however; it can be drying and irritating to the lungs. To use DE, mix 1 ounce (2 teaspoons) mixed into a five pound jar of grains. Mix 1 pound (just under 3/4 cup) in each 100 pounds of grains.