Photo: Board trap
You can trap snails and slugs beneath boards or pots that you position throughout the site. Construct wooden traps using 12- by 15-inch boards (or any easy-to-handle size) raised off the ground by 1-inch runners. The runners make it easy for the pests to crawl underneath. Scrape off the accumulated snails and slugs daily and destroy them; crushing is the most common method.
Some people use beer-baited traps buried at ground level to catch and drown slugs and snails that fall into them. Because it is the fermented part of the product that attracts these pests, you also can use a sugar-water and yeast mixture instead of beer. However, these traps aren’t very effective for the labor involved. Beer traps attract slugs and snails within an area of only a few feet, and you must replenish the bait every few days to keep the level deep enough to drown the mollusks. Traps must have deep, vertical sides to keep the snails and slugs from crawling out and a top to reduce evaporation. While they are not particularly effective for snail and slug control in production nurseries, they can be used as a monitoring method to determine if baiting or other management method should be used or to determine if current management methods are working
The information in this section has been modified from the University of California IPM website (http://www.ipm.ucanr.edu/).