MolluscIreland - land and freshwater
  • Deroceras (Deroceras) agreste (Linnaeus 1758) Northern field slug
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Deroceras (Deroceras) agreste
© Dr Roy Anderson
Deroceras (Deroceras) agreste
© Dr Roy Anderson

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A small to medium-sized field slug with a uniformly oatmeal-coloured body lacking darker spots. Mucus clear but milky when irritated. Indistinguishable externally from pale specimens of the very common grey field slug, though much rarer.

Key characteristics

  • A small to medium-sized buff or oatmeal-coloured slug without dark spots, although the grooves on the back, being slightly darker than the underlying ground colour, may give the appearance of diffuse spots
  • Mucus colourless but milky when irritated
  • Sole buff
  • Keel short, not truncate
  • Breathing pore towards the rear of the mantle
  • Differs from the grey field slug in the structure of the penial appendix

Size

25-40 mm.

World Distribution

Distributed across most of northern and western Europe into north and central Siberia. Distribution type: Eurosiberian Boreo-temperate (54).

Irish Distribution

A very rare and local slug in Ireland with only a single site, Buckroney Sands, Brittas Bay, Co. Wicklow, so far identified (Anderson, 2006). Very possibly overlooked because of difficulties in separating it from the grey field slug.

Ecology

  • The site at Buckroney is on the banks of a small stream running through grazed sand dunes with some scrub woodland
  • In Britain sites are mostly on high ground, although in East Anglia and parts of Cumbria it occurs on marshy ground by streams and fen drains at relatively low altitude

Red List status

  • Data deficient.