Deroceras (Deroceras) agreste (Linnaeus, 1758)
Rare in central Europe, central and S England. Vulnerable in Bavaria and Austria, lower concern in Germany.
Rare in central Europe, central and S England. Vulnerable in Bavaria and Austria, lower concern in Germany.
External: Mantle 1/3 body length; light brown or occasionally gray body, never with spots; lighter on sides; darker head and tentacles; slightly pale edge of pneumostome; white sole; mucus clear normally but milky when perturbed (Quick 1960; Kerney & Cameron 1979; Wiktor 1996, 2000).
Internal: Internal shell 3 mm long (Quick 1960); penis sac-like and thick-walled with a constriction; nodular or digital gland on penis; vas deferens attached under gland on side of penis apex; conical stimulator in base of penis; rectal caecum present (Wiktor 1996, 2000).
Similar to D. reticulatum, but smaller, thinner, smoother, and with less color; penial appendix is short, smooth, single appendage; ovotestis is in the middle of the visceral mass rather than toward the tail tip (Quick 1960).
Juvenile D. reticulaum, D. lothari, and D. turcicum may be mistaken for adults of D. agreste (Wiktor 1996).
Eggs: 2.2 x 2.5 to 2.5 x 2.25 mm; translucent with white calcareous particles on outside; 10-20+ eggs per clutch (Quick 1960).
Juveniles: 3.5 mm long, translucent, whitish at hatching (Quick 1960).
35-50 mm long (Quick 1960).
Native in - W Palearctic to Crimea and Central Asia. Countries occupied include Iceland, Norway, Sweden, Denmark, Finland, Estonia, Latvia, Lithuania, Russia, Poland, UK, Netherlands, Belgium, Luxembourg, France, Germany, Switzerland, Leichtenstein, Austria, Czech Republic, Slovak Republic, Hungary, Bulgaria, and countries of the former USSR (Kerney & Cameron 1979; Wiktor 1983; Falkner et al. 2001; Likharev & Schileyko, MS in Sysoev & Schileyko 2009).
Introduced elsewhere.
Mountain meadows and marshy habitats that are relatively undisturbed; to 2400 m altitude (Quick 1960; Kerney & Cameron 1979).
In Britain, eggs are laid in fall, hatchlings overwinter, slugs reach maturity in the summer to fall, and they die after mating. In Finland, the eggs overwinter and the hatchling to adult stages are much shorter (Quick 1960).
Deroceras reticulatum; juvenile D. reticulaum, D. lothari, and D. turcicum .
External: Mantle 1/3 body length; light brown or occasionally gray body, never with spots; lighter on sides; darker head and tentacles; slightly pale edge of pneumostome; white sole; mucus clear normally but milky when perturbed (Quick 1960; Kerney & Cameron 1979; Wiktor 1996, 2000).
Internal: Internal shell 3 mm long (Quick 1960); penis sac-like and thick-walled with a constriction; nodular or digital gland on penis; vas deferens attached under gland on side of penis apex; conical stimulator in base of penis; rectal caecum present (Wiktor 1996, 2000).
Similar to D. reticulatum, but smaller, thinner, smoother, and with less color; penial appendix is short, smooth, single appendage; ovotestis is in the middle of the visceral mass rather than toward the tail tip (Quick 1960). Juvenile D. reticulaum, D. lothari, and D. turcicum may be mistaken for adults of D. agreste (Wiktor 1996).
Eggs: 2.2 x 2.5 to 2.5 x 2.25 mm; translucent with white calcareous particles on outside; 10-20+ eggs per clutch (Quick 1960).
Juveniles: 3.5 mm long, translucent, whitish at hatching (Quick 1960).
Extended: to 40 mm long; preserved: ~35 mml long (Wiktor 2000).
The range of D. agreste is uncertain because it tends to be misidentified (Wiktor 1996).
Probably native to entire Europe, much of Central Asia to E Russia (Wiktor 1996); includes British Isles, Iceland, Scandinavia all the way to Sakhalin and Kuril Ids (Wiktor 2000).
Non-native to: South Africa (Herbert 2010).
May be found in disturbed habitat with D. reticulatum and D. sturanyi (Wiktor 2000).
Lowlands to 2500 m altitude in mountains; meadows, marshes, and undisturbed places, also gardens, thickets, and sometimes cultivated land (Quick 1960; Kerney & Cameron 1979; Wiktor 2000).
In Britain, eggs are laid in the fall, hatchlings overwinter, adults mature in summer-fall, and they die after mating. In Finland, D. agreste eggs overwinter, and the hatchling-adult stage is much shorter (Quick 1960).
Lives about one year (Wiktor 1996), with 1-2 generations per year (Wiktor 2000).
Can reproduce by itself (Wiktor 2000).
Herbivore or omnivore (Wiktor 1996).
Sometimes a pest of cultivated land (Wiktor 1996).