garden arion

Garden arion is a small, exotic, terrestrial, roundback slug. It is native to Europe and Great Britain. It has been introduced into North America, New Zealand, and Tasmania, Australia. It now occurs in the United States in the east from Maine to Maryland, west to Minnesota and Illinois, and south along the Appalachian Mountains to Georgia. On the West Coast, it occurs from northern Washington to southern California, but mostly around major metropolitan areas. In southern Canada, it occurs from Nova Scotia to Ontario and in British Columbia.

Garden arion is found in a variety of habitats, including woodlands, fields, pastures, nurseries, yards, and gardens. It can be a serious pest in greenhouses, gardens, and cultivated crops.

The adult is usually 1″ to 19⁄16″ (25 to 40 mm) in length, but it can be up to 2″ long. The body is long and narrow when extended, short and semicircular in cross section, not bell-shaped, when contracted. It is not ridged (keeled).

The skin is thick and is covered with raised areas (tubercles) and grooves, giving it a granular appearance. The saddle-shaped covering on the front of the body (mantle) is short but usually covers more than one third of the body. The breathing pore (pneumostome) is on the right-hand side in front of the middle of the mantle. It is difficult or impossible to see if not open. The color of the upper side is variable. Mature individuals are gray to yellowish gray above with a dark longitudinal stripe on each side. The stripe on the right side usually runs entirely above the pneumostome. The first row of tubercles above the foot fringe is white. The tentacles are bluish or reddish. The underside (sole) is yellow or orange.

The mucus is yellowish orange.

Juvenile individuals are darker, mostly dark bluish gray to completely bluish black above, and yellow below.

Total length: 1″ to 19⁄16″ (25 to 40 mm)

A variety of habitats, including woodlands, fields, pastures, nurseries, yards, gardens, and agricultural crops

Spring and fall; probably two generations per year

A batch of 12 to 80 eggs are laid in the soil every 1 to 3 weeks. Up to 200 eggs can be laid in a lifetime. The eggs hatch after 20 to 40 days. Juveniles reach maturity in about 6 to 7 months. Lifespan is about nine months.

All stages overwinter, including eggs, juveniles, and adults.

Omnivorous, but prefers fruit, seedlings, and weak young plants

Sources

24, 29, 30.

Arion hortensis
Lloyd Davies

arion hortensis slugs exploring
98AE73

Arion hortensis
Juraj Ivan

Black field slug (Arion hortensis) - Groote Heide (Netherlands) 5-9-2020
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Darla
6/11/2024

Location: 437th St, Harris Mn

I didn't take pictures, but I had two small ones and a large one, over an inch in size. These were on the cement patio by foundation of house. Saw them after dark when I took my dog out, in fact, the dog noticed the first one before I did.

This is my first spring here, I cannot say that I like having these slugs, they are so gross!

Luciearl
5/11/2024

Location: Lake Shore

I often find these immature caterpillars? Dead on the warm asphalt. There were 50-100 dead on the road. A whitish secretion trails it before dying. I picked one up. It was stuck on the road.