The marsh slug is native to North America, and is also found in South America, Europe, and Asia. It is a relative of the gray garden slug, Deroceras reticulatum (Muller), and shares manyaspects of its biology. Both are common pests of garden vegetables, field crops, and ornamentals throughout the United States and Canada. The marsh slug may be found in such habitats as forests, as well as in fields and greenhouses. The marsh slug attacks seedlings of a number of field crops, including no-tillage corn and alfalfa. It also damages lettuce, beans, and fruits such as strawberries. Slug populations may vary considerably from year to year, and are highest in wet years.