The biggest problem I've had in San Francisco has been grain weevils:
https://www.google.com/search?q=grai...eY3dmpfH9ByHM:
I like imported Italian pasta and several times I've gotten boxes of it with these things inside. The first time I didn't notice them until they escaped the packaging and infested my kitchen. I had to empty all the shelves, toss out all grain-based products and spray all the shelves. That got rid of them but now when I buy imported grain products I store them sealed in something impervious to insects.