I've been warring with "weevils" for the past month. They've gotten into a free standing cupboard where we store cook books, flour, cornmeal and other dry meal products and they're in EVERYTHING.
Through research on the internet I've found that there are some general guidelines to follow to keep them under control. Best of all it's a non-chemical approach.
Prevention
1. Freeze all meal products (cereals, flours, animal food/seed, etc) for 24 hours after puchasing in order to kill any eggs/insects that might be present in the products. The idea is to keep them from breeding once you've brought them into your home.
2. Store all food products in air tight containers. A lot of "tupperware" type containers are NOT sufficient. Ziplock bags and mason jars (rubber seal, screw-on lids) are reported to be the best. We use a vaccum sealer for a lot of items.
3. Use bay leaves in cupboards and in products to keep these little monsters at bay (pun intended). I've found tons of references to this as being a particularly effective means of control. Many people put a few leaves in their meal products.
If you've got an existing infestation
1. Inspect food packaging for sign of the insects. Worms, moths, casings, webbing, and tiny holes in the packaging itself. If you see ANY signs of them then immediately take the packaging outside and dump it in the trash. For you composters, you can dump it into your pile, but these vile little creatures are persisten beyond measure. Make sure it's a very hot pile where they'll not have the opportunity to flourish and re-infest your home. Persoanlly I'd take em out as far from my home as possible.
2. Clean every last thing that is stored in the infested space with warm soapy water. Cans, containers, books, EVERYTHING. In the cabinet where we had them we had perhaps about 50 cookbooks and they've taken up residence in at least half of them - inside hard cover spines and between pages. Ugh!!
After cleaning them out of the books, I've placed those books in plastic bags and into the freezer.
3. Remove absolutely everything from the infested storage space, even the shelves if possible and wash all surfaces with soapy water. Don't forget things like door hinges or undersides. Use some sort of brush to get at recessed or hard to wipe areas. It's war and you have to be thurough or it will never end.
4. Once every sign of these tiny demons is erradicated to the best of your ability, place bay leaves in the storage area. A few on every shelf or as needed. As noted before this is supposed to be a particularly effective detterent so don't skimp. Buy in bulk at Costco, or the like, and replace them periodically (I have no idea how long the leaves remain effective).
Hope this is helpful.
~Dave