Exotic plant pests
Giant African snail

Officers of Biosecurity, Department of Primary Industries and Fisheries

Figure 1 Giant African snail on a banana leaf and Giant African snail eggs enlarged (inset)

What is it?

Giant African Snail (GAS) Achatina fulica is one of the world's largest and most damaging land snail pests which has spread quickly around the world as it can ‘hitch-hike’ to new locations on a range of cargo types, particularly on pallets, shipping containers and vehicles. If introduced to Australia, the GAS has the potential to be a serious environmental and agricultural pest as it is capable of feeding on over 500 species of plants, a number of which are of commercial importance.

It does not occur in Australia, however it is occasionally detected "hitch-hiking" on imported shipping containers and materials. An outbreak of the pest occurred in Gordonvale, Queensland in 1977, which was subsequently eradicated. Originating in east Africa, the snail has spread to much of the Indo-Pacific (bordering mainland and island areas of the Indian and Pacific Oceans) either by accidental means or purposeful introduction by humans as an alternative food source. Also, it is very hardy and has the ability to enter a dormancy period, enabling it to survive for long periods without food. It also has a rapid reproductive rate allowing it to colonise new areas very quickly. Although GAS is a tropical snail, it can survive cold conditions, even snow, due to its ability to lie dormant.

What does it look like?

The Giant African Snail is much larger than native Australian snails. A GAS shell ranges in size from 5 to 10cm, but can measure up to 30cm and weigh 1 kg. The shell is also conical, tapering to a point as compared to a number of native snail species whose shells are mostly globular. The colour of the shell can vary, but is commonly brown with pale cream streaks.

GAS eggs, which are laid in batches of 100-400, are spherical to oval in shape, approximately 5mm in diameter and cream to yellow in colour (somewhat like miniature hens’ eggs - see Figure 1).

Where does it live?

Giant African Snails are normally active at night, emerging at dusk to feed in the open and returning to shelter at dawn. On wet days they will remain active during daylight.

The snails are commonly found under leaf litter, old roofing iron and timber, compost heaps, thickly grown ornamental shrubs and in crevices between rocks and tree roots. At night, they will often be found on barriers such as fences and house walls.

During the Gordonvale outbreak, snails were commonly found during the day at the base of banana clumps, particularly on neglected plants where there was a large amount of leaf trash.

Have you seen it?

If you believe you have seen a giant African snail, contact the DPI&F Call Centre on 13 25 23 (local call cost in Queensland). Place it into a container, such as a jar or ice cream container, with dry newspaper. Wash your hands after handling any snails. DPI&F officers will be in contact with you to provide further advice and investigate your specimen.

What does it eat?

Normally giant African snails feed on decomposing vegetation. However, when introduced to a new environment, they have been known to feed on a wide range of plants, including cocoa, rubber, banana, papaw, citrus, sweet potato, cassava, most vegetables, legumes and ornamentals. They will also consume fallen fruit, garbage, human and animal excreta - and even the bodies and shells of their own species.

How is it controlled?

The main risk of GAS introduction to Australia is via plant material, crates, shipping containers, machinery and motor vehicles. It could also be introduced in the egg stage in soil. To reduce the chance of an incursion, the Australian Quarantine and Inspection Service (AQIS) conducts targeted inspections of containers from countries which are considered high risk for GAS (see AQIS GAS website ). Imports which present a particularly high risk, such as empty pallets and ground stacked shipping containers, are fumigated.

The pest is difficult to eradicate. The successful Gordonvale eradication campaign involved an intensive eight-month program of community education, snail collection and baiting.

Information contained in this publication is provided as general advice only. For application to specific circumstances, professional advice should be sought. The Department of Primary Industries and Fisheries Queensland has taken all reasonable steps to ensure the information in this publication is accurate at the time of publication. Readers should ensure that they make appropriate inquiries to determine whether new information is available on the particular subject matter.

Last reviewed 28 April 2005