Rainforest hikers often meet the banana slug, Ariolimax columbianus , a magnificent and even dignified slug which may reach 4 inches in length, yellowish, olive or brownish, working its way through debris in woodlands. A casual gaze around any maritime Puget Sound garden reveals several distinctly different species of slugs and snails. Gardens located near woods or meadows will have more varied and larger slug populations. As is often true with garden pests, it's the immigrants that cause the most problems. All types of slugs and snails can destroy garden plants, and the problem is particularly difficult when plants have soft, tender growth.
Many plants escape slug damage.
Woody herb plants, thorny stemmed plants like barbarry, and conifers possess immunity. But slugs go for young vegetables, emerging lilies, spring bulbs, and perennials like delphinium. After a week of rainy days in early May, the damp garden is now slug and snail paradise. They require moisture in soil and vegetation. During dry or cold weather slugs can move down into soil to find dampness, often following existing worm holes or other openings.