You need a cool, well-ventilated place to store grain. The general rule is to buy only as much grain as will be consumed in three months. If you store it for longer, there is a great risk that food moths will find it.
The advantage of canvas grain bags is that they can aerate the grain, but also that the grain moves when you use them, which the moths don't like. These grain bags have an opening mechanism that can be operated with one hand.