Theba pisana

white garden snails

Biological Name

Theba pisana (O.F. Müller, 1774)

Common Name

White garden snail

Other Common Names

White italian snail, mediterranean sandsnail, sand hill snail, coastal snail

Appearance/Characteristics

The wite garden snail is a medium sized snail, 10 to 30 mm in diameter, very variable in terms of its shell appearance. The apex is dark, bluish-grey, the umbilicus is narrow and half covered by the reflected columellar margin. The shell is ivory yellow, with dark colour bands or spot, some specimens being chalky white. Juvenile shells are sharply keeled.

Other Similar Species

Cernuella virgata

Biological Notes

The white garden snail can have an annual or biennial life cycle. In the Mediterranean, it has a biennial life cycle, in Australia normally a single lifecycle per year. White garden snail climb on plants for aestivation, in hot climates they aggregate in large numbers and snails coat the stems of the vegetation. The diet of the white garden snail is wide-ranging, decaying matter is taken but it also feeds on agricultural plants. The White garden snail does not survive serious winter frosts.

Geographic Distribution

Its native range includes almost all the Mediterranean coastline, but it became an agricultural pest by accidental introduction in many parts of the world. It is established in the coastal areas of the UK, California, South Africa and Australia.

Habitat

The white garden snail is generally a species of coastal areas, in or near sandy habitats. It preferably lives in disturbed habitats, but also has invaded native habitats.

Crops at Risk

Its presence damages in vineyards, citrus orchards, pastures, vegetables, cereals, fruits, ornamental plants.

Damage Caused/Symptoms

Direct losses from consuming the crop are reported from seedlings of cereals, vegetables, ornamental plants and the ability to defoliate citrus trees. The ability of the white garden snails to aggregate in masses causes issues in clogging machinery and their bodies and shells can be contaminants in harvested crops.

Impact and Severity

The white garden snail is mainly a pest at harvest.

Prevention and Control

Minimum tillage may favour this species, ploughing will bury the snails and destroy their eggs. As the snails often migrate from adjacent areas a stripe of bare soil without organic matter and shelter can minimise migration into the fields.

Natural Predators

Birds, predatory arthropods, nematodes and other gastropods are natural predators of the white garden snail.