Weevils are tiny members of the beetle family whose larva grow within the seed casings of grain and seeds and are only seen after they burst that seed coating. They are very small--under 1/4 inch at their largest--and they make a spider web like mess inside your box or package of food. There are ways to get rid of them, but it's far better to avoid getting them in the first place.
Stop weevils easily by doing two simple things. The first thing to do is to put items prone to weevils into the freezer for four days. This will kill the microscopic larvae and prevent any weevils from hatching. Do this with your flour, corn meal, grits, rice, spices and similar items.
Store things you can't put into the freezer for four days in sealable glass or plastic canisters or in sealablel plastic bags. These include cereals, dried fruits, crackers and cookies. Weevils can even invade seeds that are stored for planting, decorative corn, bean bag toys or chairs and other inedible items where seeds and grains are used. If you have a weevil problem in a box of cereal or bag of popcorn it will be contained in one sealed bag (the store bags are not OK once they're opened) that you can throw out or empty-outside-and clean.
Attack weevils you already have by thoroughly emptying your entire pantry. Throw away anything infested by tying it closed in a plastic grocery bag and taking it outside immediately. Throw out everything that you know to be infested. For items that you aren't sure about, put all of these that you can in the freezer for that four day period. Take each item that can't be frozen but seems OK and put each one into a sealed container or zippered closure plastic bag.
Take everything out of your pantry. Vacuum your pantry out and take the vacuum outside to empty it, throwing away the bag. For bagless vacuums, take the plastic container outside and empty it and rinse it well with the hose before you take it back indoors. It takes just one weevil to start the whole process over again so it really is worth the trouble to do this very carefully.
Wash your pantry cupboards down with very hot soapy water, making sure that you get the hot suds in all the nooks and crannies. If you have shelf paper it would be best to take it out and replace it--again, throwing it away outside. Rinse the cupboards with clear hot water and a sponge or dish rag.
Let the cabinets dry and then spray them well with an insecticide that says on the label that it kills weevils. Ask at your home store or hardware store if the local department store doesn't carry this. Spray into all those nooks and crannies and then close your cabinets for four to six hours.
Put everything back into your pantry that has been put in glass or plastic or sealed bags. Wait the whole four days for those things in the freezer and then put them into containers or bags as well.
Make it a habit to put staples into the freezer for four days whenever you buy them. Always put other vulnerable items into containers and bags. Taking these little extra precautions ahead of time will save you a great deal of trouble later.