dusky slug

(Arion subfuscus/fuscus)

Conservation Status
dusky slug
Photo by Alfredo Colon
  IUCN Red List

LC - Least Concern

 
  NatureServe

NNA - Not applicable

 
  Minnesota

not listed

 
           
           
           
           
           
           
           
 
Description
 
 

Dusky slug is a common, exotic, terrestrial, roundback slug. It is native to northern Europe and was introduced into North America. It was first reported in the United States in the vicinity of Boston in 1842, and by 1940 it was widespread across North America. Molecular DNA evidence suggests that it probably came from Britain, France, or the Netherlands. It was likely introduced several times. It is found in moist or wet areas in deciduous and coniferous woodlands, in meadows on rocks, and in old fields and waste places. It is often encountered in areas of human activity, including in roadsides, gardens, campgrounds, wood piles, and window wells. In natural areas it is sometimes more abundant than native snail and slug species. It can a pest of agricultural crops, forest replantings, and gardens.

Two species of dusky slug are often treated as a single species complex, a group of species so similar that the boundaries are unclear. Western dusky slug (Arion subfuscus) is native to western Europe, northern dusky slug (Arion fuscus) is native to central, eastern, and northern Europe. Aside from their geographic distribution, the two species can only be distinguished by the size and color of the genitalia of dissected individuals, or by analysis of their alloenzymes. Both species have been introduced into North America.

The adult is 2 to 2¾ (5 to 7 cm) long. There is no shell. The body is long and slender when extended, short and bell-shaped in cross section when contracted. It is not keeled, and it does not have an elevated hump. The back plate (mantle) is about one third the total length of the body. It is covered with rows of pale bumps (tubercles), giving it a finely granular appearance. It is variable in color, but populations generally fit into one of four color groups: blackish-brown, yellowish-brown, orange, and reddish-brown. The orange or yellowish-orange color is mostly – or completely – due to a covering of mucus. When handled, the mucus will stain the handler’s fingers. There is usually an indistinct brown stripe and a lighter region above the stripe on each side extending the entire length of the body, but this is sometimes absent. The area near the foot fringe is whitish. The underside (sole) is pale yellow. It is not divided buy two longitudinal furrows. The head and tentacles are black.

 
     
 

Size

 
 

2 to 2¾ (5 to 7 cm) long

 
     
 

Similar Species

 
     
     
 
Habitat
 
 

Deciduous and coniferous woodlands, meadows, old fields, waste places, roadsides, gardens, campgrounds, wood piles, and window wells.

 
     
 
Biology
 
 

Season

 
 

Summer and fall

 
     
 

Behavior

 
 

 

 
     
 

Life Cycle

 
 

 

 
     
 

Food

 
 

Mushrooms, living and dead plant matter, fruit, and animal excrement.

 
     
 
Distribution
 
 

Distribution Map

 

Sources

24, 29, 30, 83.

 
  1/30/2023      
         
 

Occurrence

 
 

Common

 
         
 
Taxonomy
 
 

Class

Gastropoda (gastropods)

 
 

Subclass

Heterobranchia

 
 

Infraclass

Euthyneura

 
 

Subterclass

Tectipleura

 
 

Superorder

Eupulmonata

 
 

Order

Stylommatophora (common land snails and slugs)

 
 

Suborder

Helicina

 
 

Infraorder

Arionoidei

 
 

Superfamily

Arionoidea (roundback slugs and allies)

 
 

Family

Arionidae (roundback slugs)

 
 

Genus

Arion (arion slugs)

 
 

Subgenus

Mesarion

 
       
 

Subordinate Taxa

 
 

northern dusky slug (Arion fuscus)

western dusky slug (Arion subfuscus)

 
       
 

Synonyms

 
 

Limax fuscus

 
       
 

Common Names

 
 

dusky arion

dusky slug

 

 

 

 

 

 

 

 

 

Glossary

Mantle

On gastropods: the fleshy, membranous covering of the front of the body.

 

 

 

 

 

 
 
Visitor Photos
 
           
 

Share your photo of this gastropod.

 
  This button not working for you?
Simply email us at info@MinnesotaSeasons.com.
Attach one or more photos and, if you like, a caption.
 
 

Alfredo Colon

 
    dusky slug   Strict-branched Coral Fungus and dusky slug  
           
    dusky slug   dusky slug  
           
    dusky slug   dusky slug  
           
    dusky slug   dusky slug  
 

Greg Watson

 
    dusky slug      
           
 
MinnesotaSeasons.com Photos
 
 

 

 
           

 

Camera

     
 
Slideshows
 
Dusky Slug (Arion subfuscus)
Andree Reno Sanborn
  Dusky Slug (Arion subfuscus)  
Arion subfuscus
Lloyd Davies
  Arion subfuscus  
 
About

Arion subfuscus

 

 

slideshow

       
 
Visitor Videos
 
       
 

Share your video of this gastropod.

 
  This button not working for you?
Simply email us at info@MinnesotaSeasons.com.
Attach a video, a YouTube link, or a cloud storage link.
 
 

 

 
     
     
       
       
 
Other Videos
 
  estern Dusky Slug (Arion Subfuscus) During a Thunderstorm
Cool Nature Clips
 
   
 
About

May 19, 2022

 
  Arion subfuscus (Draparnaud, 1805) Dusky Arion Slug
Chin Frank
 
   
 
About

May 15, 2014

From garden in residential area, Eugene, Lane County, Oregon, May, 2014. See: https://jacksonvilleshells.org/416tts.htm

 

 

Camcorder

 
 
Visitor Sightings
 
           
 

Report a sighting of this gastropod.

 
  This button not working for you?
Simply email us at info@MinnesotaSeasons.com.
Be sure to include a location.
 
  Greg Watson
9/3/2022

Location: Eagles Bluff Park

dusky slug  
  Alfredo Colon
8/27/2022

Location: Albany, NY

dusky slug  
  Alfredo Colon
8/24/2022

Location: Albany, NY

dusky slug  
  Alfredo Colon
8/18/2022

Location: Albany, NY

dusky slug  
  Alfredo Colon
8/8/2022

Location: Albany, NY

dusky slug  
  Alfredo Colon
8/5/2022

Location: Albany, NY

dusky slug  
           
 
MinnesotaSeasons.com Sightings
 
 

 

 

 

 

Binoculars


Created: 11/19/2022

Last Updated:

About Us | Privacy Policy | Contact Us | © MinnesotaSeasons.com. All rights reserved.