Giant Snails

Scientists at Work on Most Difficult Problem in New Guinea

THE problem introduced into New Guinea, when the Japanese in 1942-45, let loose the giant snail in the Kavieng, Rabaul and Madang dis tricts, with the intention that it should provide them with an article of food, is being vigorously attacked by the Pro visional Administration’s Department of Agriculture.

The snails have increased so quickly, and the areas affected are so wide, that scientists are finding it most difficult to decide upon a course of action. The snails can be killed with poison but how can baits be scattered effectively over hundreds of square miles? Biological control seems to be the only answer.

At the present time, the Department has two Entomologists, Mr. B. A. O’Con nor, BA, BSc., and Mr. G. S. Dun, BSc., Agr., working full time, in Rabaul, on this snail problem, under the general direction of Mr. J. L. Froggatt BSc., Senior Entomologist. This team has done much original work, not yet pub lished, on snail bionomics control.

The snail introduced into New Guinea by the Japanese is a native of Madagas car; its scientific name is Achatina panthera, var. Leucostyla. It has been found by investigation that these snails can withstand desiccation for some months, by simply shrinking inside the shell and covering themselves with a pro tective skin, and thus going into a state of suspended animation.

Snails not in the active condition can “survive” for at least a couple of months of complete starvation, and can lay eggs after long periods without food. The snails are also hermaphrodites, and thus copulation is a reciprocal process, being carried on at rare intervals, and this suffices to ensure large populations.

Apart from its plant foods, the snail eats dead individuals of its own species (even when the flesh is putrid), the shells of its own species, both living and dead, dead shells of other molluscs, soil, coral rock and many other substances.

The problem of control is complex and involved. Large numbers of snails are found in areas where they have wide distribution e.g. Kavieng—and meta dehyde baits are costly, as to distribu tion and personnel involved, especially where the baits are so easily washed away by rains, so that control by this means is almost out of the question.

Biological control, and other effective methods, are being sought by these com petent investigators, and no effort is be ing spared to get the pest under control.