Theba pisana (Muller, 1774)
White garden snail, Mediterranean sandsnail, Sandhill snail, White snail
The tough, opaque shell of this species is slightly flattened (low spire). The height of the shell is 13 mm and width 18 mm with 4 1/2 whorls. However, some specimens may be smaller. The ivory yellow shell may be uniform or it may possess unequal brown stripes. These stripes or lines may be interrupted forming dots or dashes. The dull surface has fine growth lines. However, the embryonic 1 1/2 whorls are smooth.
Mediterranean region and Western Europe
- U.S.: California
Atlantic Islands: Bermuda, Canary Islands
Europe: Western France, Southwestern England and Wales, Ireland
Africa: South Africa, Somaliland
Other: Mediterranean region
Typically this snail is found in coastal, sandy areas. Theba pisana has the potential to increase in number rapidly. This species has been deemed a serious pest and and may be a nuisance because of its ability to aggregate in large numbers. It may occur in numbers of up to 3000 in one tree. This snail possesses the ability to defoliate large trees, including citrus and ornamentals. It also consumes garden crops, seedlings and cereal grains (e.g., wheat, barley, oil seeds, seed carrot and legumes). In grain producing areas this species will cause direct and indirect losses. Direct losses include clogging machinery and directly consuming the crop. Indirect losses include contaminating the grain and allowing for the infestation of the grain by secondary fungal pathogens, due to the added moisture they provide.
Theba pisana generally lays its eggs several inches below the soil surface with an average of 70 eggs per clutch. It takes approximately 20 days for the eggs to incubate; however, it may take longer in dry weather. This snail typically does not seek cool, dark places to aestivate. They preferentially attach to plants, fences, under stones or other vertical, physical structures. Longevity: 2 years.
- Helix pisana Muller, 1774, Verm. Hist., 2: 60; Taylor, 1911, Monogr. L. & Freshw. Moll. Brit. Is., 3:360, pl. 30, 31; Orcutt, 1919, Nautilus, 33:63.
Anderson 2005; Barker 2002; Cowie et al. 2009; Hitchcox and Zimmerman 2004; Pilsbry 1939; Mead 1971; Rumi and Sanchez 2010; Yildirim et al. 2004