If you buy large sacks of flour, oats or rice, you should be on guard for weevils. Weevils are small beetles that feed on whole and processed grains, nuts and seeds. Commodity grains are often treated with diatomaceous earth to kill the pests, which works well but can't get all of them. An easy way to surely kill any potential weevils in your foods is to freeze the the entire package for two days.
Photo by Danny Chapman.
Pest control expert Peder Hoyum recommends freezing as it will kill any active weevils and their eggs so that you don't have any nasty surprises when you open that 12kg bag of awesome jasmine rice. This is a good method to use on anything you buy in bulk, but is overkill to use on each box of pancake mix or oatmeal, as those products will most likely be consumed before any existing weevil eggs hatch.
It's not fun to think about the pests that could potentially be in our food, but it is much better to eliminate that concern up front for free than to have to throw away costly bulk foods later.
Weevil Control [Simple Pest Control]