Covering with a pail would only give the slugs a nice cool place to breed and munch at their leisure. I find large slugs basking under my milk cans..that sit on sand in front of DH's shop, or under bricks/rocks that boarder my beds. Slugs can get under ANYTHING. Straight ammonia? Dousing your plant and around its base with a 10% solution of water/ammonia will kill slugs on contact. If you only have a few, I would schedule a dousing every morning EARLY for awhile. In my yard slugs are the biggest nuisance where the plants are in more clay soil. Mulch/statues/decorations give them hiding places. The older the bed, the more FULL the bed the less the slugs. I am guessing that is due to hiding places for the critters that eat the slugs?

from the FAQS

http://faq.gardenweb.com/discussions/2766126/how-do-i-control-slugs-in-my-hosta-bed

try the search box at the top of the page ...

ken

http://www.gardenweb.com/gardenweb/query/hosta-slugs/topic=hosta

Thanks ... I appreciate the advise. Very helpful.