So that little critters don't appear in your bag - - or worse, in your cake!!

https://www.thespruceeats.com/flour-storage-instructions-to-prevent-bugs-spoiling-427564

I buy flour in bulk from our health food co-op, and I usually buy about 10 #'s at a time, so I ordered some 2 gallon plastic ziplock bags from Amazon (only place I could find them) and I store my flour first in a smaller bag, and then the smaller bag goes inside the 2 gallon bag. Then the whole thing goes into the deep freezer in the basement. 

We have one deep freeze (upright) for meats and lard and marrow bones, etc., and another freezer for veggies, fruits, ice cream, and other frozen goodies (chest type).  I baked kuchen last week, so we have four of those right now but they won't last long when my son and oldest grandson find out they're in there, so I doubt they'll take up freezer space for long!