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NATURAL HISTORY
Hamadryad, Kraits and Corals prey almost exclusively on other snakes. Several species of sea snakes, all venomous, are found in Hong Kong waters but have never been known to attack bathers. An amphibian of special interest is the Hong Kong Newt, which has not been recorded anywhere else in the region.
Of the 214 recorded species and forms of colourful butterflies, several in their larval forms cause considerable damage to farmers' crops. These include the two commonly found species of Cabbage Whites, the Swallowtails, and the beautiful but less commonly found Small Blue. Among the many local moths are the giant silkworm moths. These include the Cynthia, the Fawn and Golden Emperor, and the Atlas and Moon moths. The Atlas has an average wing span of nine inches and the Moon seven inches. Two of the local plant bugs are noted for their colour and shape. They are the rare and beautifully spotted Tea Bug which has only been recorded on hill-tops, and the Lantern Fly which has delicately coloured wings and a remarkably long fore- head. Dragon and damsel flies are commonly found, as are wasps and metallic- coloured beetles. Of particular interest is the Large Spotted Batocera Long-horn Beetle, which feeds on mountain tallow trees.
Since its introduction in 1938, the African Giant Snail has become a major pest of vegetable crops and gardens, but in 1976 the snails were late in emerging after the winter and were reported in much lower numbers than in previous years. However, there seems little chance of eradicating this largest terrestrial mollusc. There are currently half a dozen other species of snails which are particularly common pests of vegetables and also several slugs, including Veronicella—a large black slug sufficiently different from all other slugs to be placed in a separate family.
Aquatic Life
Marine life forms in Hong Kong are diverse and mainly tropical in character, comprising a relatively large number of commercially important species of fish, crustacea and molluscs. The discharge of the largest fresh water system in South China to the west, and the prevailing influence of offshore water masses in the northeast, have created a situation where the westerly sector of Hong Kong has a predominantly brackish water fauna, while the eastern sector has a genuine marine fauna.
The waters of Hong Kong serve as a nursery ground for a variety of fishes, especially in the Sparidae, Lutjanidae, Carangidae, and isospondylous groups. The abundance of these and other juvenile fishes in summer attracts large-sized transient predators, including the Little Tuna, Sailfish, Dolphinfish and sharks.
Certain coastal fish groups form viable inshore fisheries-notably the Pomfrets, White Herring, Hilsa Herring, Gizzard Shads, Threadfin, Yellow Croaker, Scads, and Japanese Sea Perch. But the relative abundance of some of these and other species has declined. Squids and cuttlefishes are also seasonally exploited by the inshore fishery. A recent form of resource utilisation is the fattening of natural wild stock of fish fry in floating net cages.
From time to time dolphins are sighted in Hong Kong waters and identifications have included the Common or Saddle-back Dolphin (Delphinus delphis), the Black