MolluscIreland - land and freshwater
  • Deroceras (Deroceras) invadens Reise, Hutchinson, Schunack & Schlitt 2011 Tramp slug
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Deroceras (Deroceras) invadens
© Dr Roy Anderson
Deroceras (Deroceras) invadens
© Dr Roy Anderson
Deroceras (Deroceras) invadens
© Dr Roy Anderson

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A very active, small to medium-sized slug varying from grey to dark brown in colour, with a grey sole, pale-ringed respiratory pore and colourless mucus. An introduction from the Mediterranean found widely in disturbed places.

Key characteristics

  • A small to medium-sized slug either brown to dark-brown in colour with darker flecks or else a translucent grey to pinkish-brown
  • Mucus colourless
  • Sole grey
  • Keel short, truncate
  • Respiratory pore ringed paler
  • Respiratory pore towards the rear of the mantle

Size

25-35 mm.

World Distribution

According to Giusti et al. (1995) this is a native of Malta, Sicily and several Italian islands i.e. with a Tyrrhenian distribution. Recent work by Reise et al. (2011) has shown that the species name panormitanum in use by other authors including Giusti et al. refers to a less well known and very local species which is not as invasive as the tramp slug. The latter has now been renamed Deroceras invadens. It has been introduced by man to west, central and northern Europe, North America and Australasia.

Irish Distribution

The invader slug was first recognised here in the nineteen-fifties under the name Agriolimax caruanae (Makings, 1959). It is now widespread and abundant in all but extreme western districts and is still colonising western islands.

Ecology

  • Commonest in gardens and disturbed places
  • Also fairly frequent in hedgerows and drier types of broadleaf woodland
  • Commonly spread by garden rubbish left at roadsides or by plants purchased in garden centres
  • Not observed at altitudes above 250m and rare in wet habitats or peatlands where it is usually replaced by Deroceras laeve

Taxonomy

This species has had many name changes. Deroceras caruanae was once applied but then synonymised with D. panormitanum, a name still widely in use. The true D. panormitanum is recorded by Reise et al. (2011) from Sicily and Malta whereas D. invadens is not associated specifically with these places and its country of origin remains unknown.

Red List status

  • Not applicable.