Chocolate arion vs Common Roller

Arion rufus compared with Ancylis badiana

Key Differences

• Chocolate arion is Vulnerable while Common Roller is Least Concern.

Taxonomic Classification

Rank	Chocolate arion	Common Roller
Kingdom same	Animalia (Animals)	Animalia (Animals)
Phylum	Mollusca (Mollusks)	Arthropoda (Arthropods)
Class	Gastropoda (Gastropoda)	Insecta (Insects)
Order	Stylommatophora (Stylommatophora)	Lepidoptera (Butterflies & Moths)
Family	Arionidae	Tortricidae
Genus	Arion	Ancylis
Species	Arion rufus	Ancylis badiana

Evolutionary Relationship

Chocolate arion and Common Roller share a common ancestor at the Kingdom level: Animalia. (Animals)

Conservation Status

Chocolate arion

VU — Vulnerable

Common Roller

LC — Least Concern

Physical Characteristics

Attribute	Chocolate arion	Common Roller
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Chocolate arion

Habitat

Inhabits temperate broadleaf and mixed forests and Mediterranean forests and woodlands within the Palearctic biogeographic realm. Populations are also found in montane and highland environments at higher elevations.

Range

Found across Europe (7 countries) and North America (United States). Currently classified as Vulnerable on the IUCN Red List, this species faces significant conservation challenges across its range.

Common Roller

Habitat

Typically found in virtually all terrestrial and freshwater habitats.

Range

Distributed across Belgium, Denmark, Norway, and Sweden.

Chocolate arion

The Chocolate Arion (Arion rufus), also known as the Large Red Slug or Chocolate Slug, is one of Europe's largest terrestrial slugs, with adults reaching up to 15 centimetres in length. It belongs to the family Arionidae within the phylum Mollusca, and despite its common name, adults display highly variable colouration ranging from reddish-orange to dark brown and nearly black — only certain colour morphs exhibit the chocolate-brown hue that partly inspired the name. Arion rufus is native to western and central Europe, where it inhabits woodland, hedgerows, gardens, agricultural land, and other moist habitats. It is also established as an introduced species in parts of North America. Like other arionid slugs, it is primarily a detritivore and herbivore, consuming dead plant material, fungi, living plant tissue, and sometimes carrion. It shelters under logs, stones, and leaf litter during dry or cold conditions, becoming active — particularly at night — during warm, moist weather. Chocolate arion can cause significant damage to gardens and crops. Reproduction is hermaphroditic; slugs exchange sperm and lay batches of translucent eggs in soil or under debris. The IUCN classifies this species as Vulnerable, reflecting pressures on native European populations from habitat change and, possibly, competition and hybridisation with related Arion species.

Common Roller

<em>Ancylis badiana</em>, the common roller, is a small moth in the family Tortricidae, order Lepidoptera. It is distributed across northwestern Europe, with documented records from Belgium, Denmark, Norway, and Sweden, typically inhabiting woodland margins, hedgerows, scrubland, and areas where its larval host plants are abundant. The species is assessed as Least Concern on the IUCN Red List. Tortricid moths in the genus Ancylis are commonly known as "rollers" or "leafrollers" because their larvae typically roll or fold leaves of host plants to create sheltered feeding structures. <em>Ancylis badiana</em> larvae feed on the foliage of various herbaceous plants, particularly species in the pea family (Fabaceae). Adults are small moths with intricately patterned wings that provide camouflage against bark and plant material. Adult moths are primarily nocturnal and are attracted to light, while larvae are cryptic within their leaf shelters. Biological traits such as lifespan, body measurements, and detailed diet host range remain poorly documented beyond general family-level characteristics. The species typically completes one to two generations per year in temperate European climates, overwintering as pupae. It is considered a minor component of invertebrate biodiversity in European lowland habitats.

Shared Countries

Both species can be found in 4 countries:

🇧🇪 Belgium 🇩🇰 Denmark 🇳🇴 Norway 🇸🇪 Sweden