MolluscIreland - land and freshwater
  • Tandonia budapestensis (Hazay 1880) Budapest slug
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Tandonia budapestensis
© Dr Roy Anderson
Tandonia budapestensis
© Dr Roy Anderson

Map hosted by the National Biodiversity Data Centre, Waterford
To view the species profile on Biodiversity Maps and access the live map, please click on the map.


A medium-sized keeled slug, yellowish-grey above to dark grey-brown or almost black, with a reticulate pattern of black spots. Keel yellowish but may be the same colour as the body. No lateral bands. Sole pale grey with a dark grey to blackish central strip. Mucus colourless. Very slender when crawling. Widespread.

Key characteristics

  • A medium-sized keeled slug, elongate when at rest and sometimes curled into a U-shape
  • Colour mostly dark, grey-brown to black, occasionally lighter, with a reticulate pattern of dark spots
  • Keel light, yellowish, occasionally concolourous with the body
  • Mucus colourless, sticky
  • Sole pale with a darker central strip
  • Mantle granulate with deep horseshoe-shaped groove


50-70 mm.

World Distribution

Originally with a south-eastern range in Europe but has spread north-westwards by human agency to reach the British Isles in 1921 (Philipps and Watson, 1930).

GBIF distribution map [open in new tab]

Irish Distribution

Widespread and common.


  • Widespread and locally abundant in richer, shaded soils
  • A common garden pest
  • Probably a pest of root crops such as potato in Ireland

Red List status

  • Not applicable.

Wikipedia link

Wikipedia page for Tandonia budapestensis

 Anderson, R., (2016). Tandonia budapestensis (Hazay 1880). [In] MolluscIreland. Accessed on 2024-03-02.