The species list contains two families of slugs (Arionidae, Limacidae) plus one species (Derocerus reticulatum) that are non-native species as well as one snail non-native family (Oxychilidae). They are summarized here. Other non-native species of land snails are also found in Indiana. A few are found in the museum records, but most can be found among iNaturalist observations. Not all the observations have received confirmation, so the distribution may differ and some identifications may be incorrect.
Each of these families or species are briefly listed below a short commentary based on the following sources: further information can be found in an excellent section (Land Snails and Slugs Without Borders) in Dourson (2010), Dourson (2015), and The Texas Invasive Species Institute (http://www.tsusinvasives.org/home/).
Arion slugs are a group of invasive species of European origin. Some can damage agricultural crops and ornamental plants, while some are garden pests. They may be found around foundations, window wells (along with other snails and slugs). They can compete with native slugs. Very few were listed in the databases. In fact, Nature Serve only notes Arion fasciatus as being in Indiana. But invasives (or exotics) could be around. It is safe to say that the actual species present and their general locations are not known. It is possible that some species of Arion not listed here might be present as well. This is a start, anyway. The Indiana map shows any occurrence of an Arion slug in the databases.
The Gray Fieldslug (Deroceras reticulatum) is an exotic species which can be found in gardens and fields, is an agricultural pest, and is also found in degraded habitats as are many non-native slugs. Its relative, the Meadow Slug Derocerus leave, is considered native, but is found as an exotic in some states. It may have originally been introduced, but it is well-established.
Asian Tramp Snail
Bradybaena similaris (Ferussac, 1821)
Counties: Hamilton and Parke
The Asian Tramp Snail was introduced via the plant trade and probably spreads with in the US that way. It has also spread into other countries. Size: 12-16 mm diameter. It eats a wide range of living plants. More Information.
Four Helicid snails are non-native with very limited distribution.
Grove (Brown-lipped) Snail
Cepaea nemoralis (Linnaeus, 1758)
This snail is typically found in urban and residential areas associated with degraded edge habitats. More Information.
Cornu aspersa (Muller, 1774)
Counties: Decatur and Hamilton
This species, introduced from Europe, is found in mostly degraded habitats of cities and urban areas. It may be a problem in gardens.
Roman Snail (Burgandy Snail, Escargot)
Helix pomatia Linnaeus, 1758
This snail of many common names is a European snail that made its way here. It is the snail of “escargot” you find on your grocer’s shelf.
Otala lactea (Muller, 1774)
This species originated in the eastern Mediterranean and North Africa and found its way here probably in plant or fruit trade. It is a fruit and plant feeding snail. More Information.
Carthusian (Chartreuse) Snail
Monacha cartusiana (Muller, 1774)
Counties: Lake, Porter, Laporte, St. Joseph
This species, as is the Milk Snail, is native to the Mediterranean region, but also to southeastern Europe. It tends to prefer grassy areas. In Indiana, its range seems limited to the northeast part of the state near Chicago and Gary – perhaps sources of entry. More Information.
This family includes two species: the Yellow Gardenslug, Limax flavus, and the Giant Garden Slug, Limax maximus. These slugs are of European origin and are found around houses, foundations, (or in basements), gardens, parks, and so on, associated with damp human structures and degraded habitats. Their size (length and bulk) is an obvious identifier. Their distribution in the state, especially Limax,is wider than shown on the maps (as indicated by iNaturalist posts).
See more on these two Limacidae in the Slugs Page.
A third Limacidae is not in the species list - the Threeband Gardenslug.
Ambigolimax valentianus (A. Férussac, 1821)
Counties: Hamilton, Hancock, Hendricks, Marion, Orange, Pike, Vanderburgh, Warrick
Image (note - slugs are sometimes difficult to identify with images only)
The Threeband Gardenslug is native to Europe’s Iberian Peninsula (Portugal and Spain), but is has spread in greenhouses and degraded habitats.
The three species are all European species introduced into the US: the Cellar Glass-snail Oxychilus cellarius, the Dark-bodied Glass-snail Oxychilus draparnaudi, and the Garlic Glass-snail Oxychilus alliarius. They may be found in urban areas including gardens (both landscaped and vegetable) (Dourson 2010, 2015). They may be transported in the landscaping plant trade (Bergey et al. 2014).