Why you should pay attention to the flour you buy at Costco

Costco is one of the most popular all-purpose retailers out there, and it's not just for their $1.50 hot dog and soda combo at the food court (although that's definitely part of it). There aren't many other stores where you can pick up a 25-lb bag of flour, a massive wheel of Parmesan cheese, and a TV while taste-testing free samples the whole way. And it's worth the aching arms to haul home an enormous bag of flour that you know will last for months, if not longer. Unfortunately, all your flour stockpiling plans can go out the window with one unpleasant discovery: bugs.

One Reddit user recently claimed to have problems with the quality of flour they bought at Costco, finding it crawling with bugs a few weeks after storing it. They also claimed to have bought and stored similarly sized bags of flour from Sam's Club without a problem. The poster wasn't specific about what kind of bugs they found, but the most likely answer is flour beetles (sometimes also called flour bugs or flour weevils, according to Extra Crispy), and they can infest almost any kind of flour, no matter where you bought it.

How to get rid of flour bugs

Flour beetles are tiny — according to The Spruce, they're about one-fifth of an inch long, and can be black or reddish brown in color. Still, no matter how small they are, you'll definitely notice the dark-colored bugs crawling around if they make their way into your flour or rice. And whether or not they end up in your grains doesn't have much to do with where you buy them from. According to Extra Crispy, the bugs can invade your bag of flour at almost any stage during the packaging and shipping process, including at the grain mill and storage warehouses. Pest control company Orkin notes that the weevils can lay eggs in your flour, rice, or cereal, which then hatch into creepy-crawly bugs.

If you bring home a bag of flour from the store and you immediately find that it's crawling with bugs, your best bet is to take it back and exchange it for a new one, or just toss it out. However, there are a few steps you can take to make an infestation less likely. First, make sure you're properly storing your flour. According to The Kitchn, grain weevils can (and will) chew right through the paper bag your flour is sold in, so it's best to transfer it to an airtight, resealable plastic container as soon as you can.

Freezing your flour for at least one week can also kill any eggs before they hatch and prevent an unpleasant discovery later. There's no guarantee you won't eventually get unlucky and bring home unwanted pests (no matter where you buy your flour), but proper storage and a quick stop in the freezer can help keep that bulk bag of flour bug-free.