(O. F. Müller, 1774)
The distribution of Deroceras laeve was originally Palearctic, from the subpolar zones to the southern margins. Today this slug species has been introduced worldwide except Antarctica, also on tropical islands such as New Guinea and on Pacific islands.
- British Isles: Great Britain and Ireland. The species has shown little evidence for significant decline in Britain.
- Czech Republic - least concern (LC)
- Switzerland - lower concern in Switzerland
- and others
- El Hatillo Municipality, Miranda, Venezuela
- introduced to Dominica (first report in 2009)
- and others
The slug is from brown to dark brown, usually with dark and characteristic but not well visible spots arranged in groups. The shape is almost cylindrical, posterior end is abruptly widened. The mantle covers 50% of body length (unusually large). There are wrinkles on skin present (may disappear in preserved slugs). Mucus is thin, colourless.
This slug is 15–25 mm long when preserved.
The populations of this species that occur in Central Europe are much darker than other Deroceras species in that area.
Reproductive system: Penis is often reduced, elongated if present, without proper penial gland but with two or more tiny glandular papillae and its end. Retractor is unforked and attached at half penis length, stimulator small, cone-shaped but looks more like a papilla. Tubular oviductus and atrium are unusually long. There is no rectal caecum.
Deroceras laeve has high ecological tolerance, but needs permanently wet habitats. It is usually found in lowlands and very humid habitats, swamps, riversides, wetlands, especially alder and oak woods, marshlands and degraded areas, also greenhouses, often near water under wood or detritus. It tolerates subpolar and tropical temperatures. Newly created habitats are often colonized after a few years. In Switzerland in up to 1800 m altitude, but usually below 1000 m, in Bulgaria in up to 2500 m.
Deroceras laeve can be a serious pest in greenhouses. On the other hand, the species is threatened by continuous elimination of wet habitats by drainage, construction projects and road construction.
The eggs of this species can also survive when submerged; juveniles can hatch underwater and then climb to the surface.
The life cycle is extremely short, and can take place within less than a month. This species can have up to 5 generations in a year, with several generations alive at the same time. Frequently there are forms with a reduced penis, which reproduce by self-fertilisation. The maximum age of this slug is not more than 1 year.
Parasites of Deroceras laeve include:
This article incorporates public domain text from the reference 
- "IUCN Red List of Threatened Species". Retrieved 27 December 2016.
- Müller O. F. (1774). Vermivm terrestrium et fluviatilium, seu animalium infusoriorum, helminthicorum, et testaceorum, non marinorum, succincta historia. Volumen alterum. pp. I-XXXVI [= 1-36], 1-214, [1-10]. Havniæ & Lipsiæ. (Heineck & Faber).
- "Synonyms of Limax laevis (n=17)". AnimalBase, accessed 4 January 2011.
- Species summary for Deroceras laeve. AnimalBase, accessed 4 January 2011.
- (Czech) Horsák M., Juřičková L., Beran L., Čejka T. & Dvořák L. (2010). "Komentovaný seznam měkkýšů zjištěných ve volné přírodě České a Slovenské republiky. [Annotated list of mollusc species recorded outdoors in the Czech and Slovak Republics]". Malacologica Bohemoslovaca, Suppl. 1: 1-37. PDF.
- Juřičková L, Horsák M, Beran L (2001). "Check-list of the molluscs (Mollusca) of the Czech Republic". Acta Soc. Zool. Bohem. 65: 25–40.
- Balashov, I.; Gural-Sverlova, N. (2012). "An annotated checklist of the terrestrial molluscs of Ukraine". Journal of Conchology. 41 (1): 91–109.
- Hlaváč, J. Č. (2004). "A new record of Deroceras laeve (O. F. Müller, 1774) from Pakistan (Gastropoda: Pulmonata: Agriolimacidae)". Folia Malacologica. 12: 181–182.
- Wiktor, A.; De-niu, C.; Wu, M. (2000). "Stylommatophoran slugs of China (Gastropoda: Pulmonata) – prodromus". Folia Malacologica. 8 (1): 3–35.
- K. T. Shao (ed.). "Deroceras laeve (Müller, 1774)". Catalogue of life in Taiwan. Biodiversity Research Center, Academia Sinica, Taiwan. Retrieved 27 December 2016.
- Rory J. Mc Donnel; Timothy D. Paine; Michael J. Gormally (2009). Slugs: A Guide to the Invasive and Native Fauna of California. ISBN 978-1-60107-564-2.
- Hausdorf B (May 2002). "Introduced land snails and slugs in Colombia". Journal of Molluscan Studies. 68 (2): 127–131. PMID 12011238. doi:10.1093/mollus/68.2.127.
- Robinson D. G., Hovestadt A., Fields A. & Breure A. S. H. (July 2009). "The land Mollusca of Dominica (Lesser Antilles), with notes on some enigmatic or rare species". Zoologische Mededelingen 83 http://www.zoologischemededelingen.nl/83/nr03/a13
- Michigan Department of Natural Resources and Environment. "Brainworm". accessed 14 December 2010.
- Spencer, H.G., Marshall, B.A. & Willan, R.C. (2009). Checklist of New Zealand living Mollusca. pp 196–219 in Gordon, D.P. (ed.) New Zealand inventory of biodiversity. Volume one. Kingdom Animalia: Radiata, Lophotrochozoa, Deuterostomia. Canterbury University Press, Christchurch
|Wikimedia Commons has media related to Deroceras laeve.|