And, when I asked about this on another forum, some documentation was provided that snails and slugs were, or could be, used. We have all seen old wheels with a hole in the hub - that was to drop snails into, then they were tamped down with a stick. Obviously would not work well on the prairie.
Re lighting.
Was olive oil too expensive to use for lighting? It gives a good light, doesn't give off horrid odors, and has a long history as a lamp oil.