Mollusks are a large and diverse group of animals of worldwide distribution.
The slugs and snails are much like some insects in their biology. Their damage to ornamental plants resembles that done by caterpillars or wireworms. Approximately 725 species of land snails and about 40 species of slugs are now known from North America. Most of these have been introduced accidentally. With few exceptions, native species are solitary in habit and do little or no damage.