Living 65 miles from the grocery store (well ... there was a convenience size store pretty close ... but it was expensive) and loving to bake my Mom always stocked up on sugar and flour.
Just like you, she kept them in big, airtight containers. Worked great. Flour would only get buggy if she left it open.
Remember, though ... if you're hungry, you can sift the bugs out and still use the flour for cooking. Gross, but people have done it for a long time before current food storage methods. And if you're hungry, you'll be glad to have it.
"A coward dies a thousand deaths; the valiant taste of death but once."
Atheists will believe anything to avoid the truth.