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The following is taken in part and modified from Kerney and Cameron (1979), Cain (1984) and Cowie (1984a). More detail is provided by Taylor (1906-1914). Adult shell up to 20 mm high and 25 mm wide, though rarely this big and more normally around 15-18 mm wide. Shell slightly depressed globular (wider than high), with 5½-6 slightly convex whorls with shallow sutures. Umbilicus narrow, and partly obscured by reflected columellar lip. Mouth of adult shell elliptical, with an internal thickening (no outwardly reflected lip) and sometimes a pinkish flush. Juvenile shell with a sharp keel at the periphery (mid-line of the shell), becoming rounded as the shell grows to adulthood. Shell sculpture of growth-ridges crossed by fine spiral striations. Shell white or off-white, rarely pink, either plain or with spiral patterning of lines (translucent, pale yellowish, dark brown or blackish), which may be broken transversely into dots and dashes, augmented with feathering along their edges, or fused to varying extents producing arrow-head shapes, chevrons and blocks. Patterning may only appear on later whorls.

Recoginition

Detection is straightforward. Adult snails are normally 15-18 mm in width and readily seen, especially as they tend to rest or aestivate on the plants above the ground during the day and in hot conditions. Juveniles are smaller but are also quite readily seen. Usually population densities are high, making the snails even more readily visible. Detection and inspection is by visual searching. Searching should be focussed on plants, fences, and other vertical surfaces on which the snails rest exposed well above the ground surface, especially in sandy areas. Shipping materials (crates, pallets, containers) coming from areas where the snails are known to exist should be examined. Although generally readily visible, nooks and crannies in containers and shipping materials and cargo should be carefully searched.

Related invasive species

  • Theba pisana

Related Farm Practice

  • Feeding
  • Damage
Impact

T. pisana is a medium-sized snail with a sub-globular, generally white or off-white shell that often bears a complex pattern of darker markings. It is generally a species of coastal habitats with warm to hot and arid climates, although it extends into cooler and wetter habitats in northwest Europe. Its range includes almost all the Mediterranean coastline, extending up the Atlantic coast of Europe. The extent to which this range is natural is not certain. Morocco has been suggested as its region of origin. Beyond this European/Mediterranean range, the major regions to which it has been introduced are South Africa (first recorded 1881), Australia (1890s) and California (1914), in all three regions rapidly becoming an invasive pest. It is frequently intercepted by quarantine officials both associated with shipments of goods and in personal luggage, indicating that it is both accidentally and deliberately transported over long distances. It is also readily transported relatively short distances, for instance attached to vehicles. Once introduced, its high rate of growth and reproduction and ability to reach extremely high population densities make it a potentially serious and difficult to control pest. It is listed as a potential pest of quarantine significance in the United States.

Has Cabi datasheet ID
62094
Symptons

Damage is by external feeding and most, if not all above ground parts of the plants are susceptible, perhaps with the exception of bark of well established trees. In most cases the symptoms are obvious – external damage to the plant. Also, the snails congregate on the affected plants in large numbers;their copious slime trails may be especially visible;and, when they leave their resting/aestivation sites on the plants, the remaining dry, white, calcareous epiphragms that they used to seal themselves to the plants may be visible.

Oss tagged
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