Agreed, unless you can run through your 50-pounds of flour in less than a month, the flour should be stored under refrigeration or better yet, freezing conditions. Even though the flour is run through an entilator at the mill there are always some insect eggs that survive the process, they will hatch into larvae (many call them "worms") in less than 28-days, depending upon when they were laid prior to milling. In any case it takes roughly 28-days from egg to mature insect (most likely confused cigarette beetles) where more eggs are laid and the population explosion begins. You can usually find these insects either on top of the flour or more commonly around the top edge of the bag, just above the flour where they are looking for a place to fly from to increase their infestation. Refrigerating the flour greatly slows the life cycle and freezing the flour for 45-days will kill any eggs that are present, then you can transfer the flour to the fridge for long term storage if you wish. Considerations: Flour is VERY DIFFICULT to freeze. A 50-pound bag might take as long as two weeks just to freeze (yes, it's that good of an insulator) you can get much more effective freezing by breaking the flour down into smaller bags (I use 5-pounds in a bag). Sperry is an organic flour and as such, it deteriorates to a great extent after only 2-weeks of storage at room temperature so if you use an organic flour it really must be refrigerated to maintain its quality. Ditto for whole-wheat flour too.
I hope this helps.
Tom Lehmann/The Dough Doctor