What can I pack with my rubbermaid containers to keep bugs out?

My sister is moving soon, she has purchased some containers to put her precious things in, her things will probably be stored in a shed for a while. I told her she may need something in their to keep bugs out but not moth balls or cedar because it will smell like that for a while. I have had things stored in my containers and some of them had spider eggs in them, somehow. Do you have any suggestions?