Giant African snail

An exotic pest – not wanted in Australia

Giant African snail is one of the world’s largest, most invasive and most damaging snails, capable of feeding on over 500 plant species, posing a serious risk to Australia’s horticultural indstries.

Keeping giant African snail it out of the country is a national priority.

What should I do?

• Report it immediately.
• Share your photos with us using the online public reporting form.
• Call the Exotic Plant Pest Hotline 1800 084 881.
• Please take good-quality photos of the pest and/or damage to include in your report. For tips, see our guide to taking good photos.

Why is it a pest of concern?

The exotic giant African snail(Lissachatina fulica) (Figure 1) is a ferocious eater of over 500 plant species. Most damage is caused to vegetable crops, flowers and ornamentals.

The snail can also spread bacteria, fungi and parasites to plants, animals and humans – such as ‘rat lung worm’, a nematode that can cause meningitis in humans. Do not pick up these snails without wearing gloves.

The snail is a nuisance in large numbers due to the stench from dead and rotting corpses.

Where to look

Giant African snails are active at night, spending their days hiding in leaf litter, piles of debris or other dark, damp places protected from the sun.

Snails can be seen travelling along fences and walls after dusk and sometimes on rainy, overcast days.

The snails can be found on machinery, motor vehicles and equipment, and as eggs in soil.

Pest profile

Appearance

• Adults: Large shells are usually between 50mm and 100 mm long, but can be up to 200 mm and weigh up to 1 kg. The shell is long and conical-shaped, half as wide as long, generally light brown with alternating brown and cream bands and faint yellowish vertical markings on the upper ridges or whorls. Diet and environment influence shell colour variations. There is a golden variety with a yellow body and shell. Fully grown snails have 7 to 9 whorls on their shells (Figures 1 and 2).
• Immature (juveniles): Smaller versions of the adult and do not have all whorls developed.
• Eggs: Spherical to oval shaped and measure 4.5 mm to 5.5 mm in diameter. Their colour ranges from cream to yellow (Figure 3).

Host plants in Australia

• Potential hosts range from Australian native and naturalised plants to agricultural crops across multiple ecosystems.
• Important economic crops including banana, bean, breadfruit, cabbage, cacao, carrot, cauliflower, cassava, cotton, cucumber, eggplant, marigold, melons, noni, okra, papaya, peas, pumpkin, sponge gourd, taro and ornamental plants.

Life cycle

Giant African snails are hermaphroditic with both male and female organs, but reproduction cannot occur without a mate. Both partners in a mating pair will produce offspring.

In ideal conditions eggs hatch 11 days after being laid, with snails becoming sexually mature after 6 months. Each snail can lay up to 1200 eggs in a lifetime.

Lifespan is generally 3 to 5 years, but the snails can hibernate for years in drought conditions.

Distribution and dispersal

• Originally from the east coast of Africa, it has now spread to south and south-east Asia, Oceania, the USA and Canada.
• Giant African snails can hitchhike in shipping containers, crates, machinery and motor vehicles.
• Eggs are found in soil associated with imported goods.

Prevention

Monitor imported cargo, host plants, soil and illegal importation as pets to prevent the introduction of the pest.

Image credits

Figure 1: Giant African snail adult. Andrew Derksen, USDA-APHIS, bugwood.org (CC BY-NC 3.0 US).

Figure 2: Giant African snails on papaya. Scot Nelson, Flickr 2011, public domain (CCO 1.0).

Figure 3: Giant African snail eggs at the base of a papaya stem. Scot Nelson, Flickr 2011, public domain (CCO 1.0).