Twentieth Century Impressions of Hongkong, Shanghai, and other Treaty Ports of China/Butterflies

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BUTTERFLIES.


By J. C. Kershaw.


Hongkong Island, protected more or less from the ravages of the Chinese wood and grass cutters, has become a haven of refuge for butterflies on the coast of Kwangtung. Nearly all the species found on the adjacent mainland are here abundant, and some inhabit the island which do not occur again till we reach some Buddhist monasteries many miles inland, around which a fair amount of well-grown timber and little-disturbed underwood is still preserved.

There are some 146 Hongkong butterflies recorded. About sixteen are rare, and two or three of these are exceedingly rare—merely accidental—though the list of rare visitants is sure to be gradually increased. But we may say that 130 species are native and numerous, the majority very abundant. The greater part are also very beautiful insects, some even gorgeous, and the butterfly fauna as a whole has a decidedly "tropical" aspect; the large and showy Papilioninæ; of which twelve species are very common, contributing greatly to its character.

Hongkong is in Wallace's Indo-Chinese (or Himalayan) sub-region of the Oriental Region. The butterflies (and also the bugs or Hemiptera-Heteroptera) have decided Indian affinities, and many insects of both orders are familiar natives of Calcutta. Hongkong is rich in representative Himalayan genera. The only two peculiar Hongkong (and South China) species, Clerome eumeus and Gerydus chinensis, belong to tropical and Himalayan genera, Clerome being entirely Oriental. The very common Euplœa midamus is a Chinese variety, slightly different from the type. Parnara sinensis, first found by Leech in Western China, is fairly common here. Two insects, Vanessa cardui and Limenitis sybilla, are respectively the well-known "Painted Lady" and "White Admiral," but the latter is scarce in Hongkong, whilst the former is spreading gradually over the world, and is not at present common here. Only two really Palæarctic genera occur here—Vanessa and Argyunis, the former represented by three species, one of which (V. indica) somewhat resembles the "Red Admiral"; the latter genus has only one species which is common in the Eastern tropics. Butterflies of the sub-family Danainæ (which is really tropical, though some of its members are rapidly becoming cosmopolitan) and genus Euplœa are some of the most abundant and striking insects in Hongkong, the Euplœa being entirely confined to the Oriental and Australian Regions, but chiefly numerous in the former. Danais chrysippus is very common here, occurs in South Europe, and is spreading over the greater part of the world, as also is D. archippus (D. crippus menippe), which has occurred in Hongkong—together, it would seem, with the spread of the food-plant of its larva, which is sometimes planted in gardens, though originally a North American weed. But the Danaid larvæ feed largely on plants which have the seeds naturally adapted for conveyance to enormous distances by the wind.

One slow-flying Pierid, P. canidia (a contrast to the rapid flight of most butterflies here) reminds one strongly of the destructive European "Cabbage White," and is, I believe, merely an Eastern race of P. rapæ. It is practically the only butterfly in Hongkong which damages gardens, as its larva feeds on cultivated vegetables. The larva of a "Skipper" Parnara Guttatus, feeds on the leaves of the rice-plant, but is greatly checked by parasites, and does no material damage.

Taking the 130 really native Hongkong butterflies, and reducing the Danainæ to the genera Danais and Euplœa (both these genera are usually sub-divided into numerous sub-genera), they are distributed as follows:—

Genera. Species. Total
species.
Danainæ  2 Danais… 7
Euplœa… 3
10
Satyrinæ  4 Lethe… 2
Mycalesis… 1
Melanitis… 1
Yphthima… 1
 5
Morphinæ  2 Discophora1
Clerome… 1
 2
Nymphalinæ 17 Cethosia… 1
Cupha… 1
Cirrochroa1
Atella… 1
Symbrenthia1
Argynnis… 1
Vanessa… 3
Precis…… 5
Hypolimnas1
Ergolis… 1
Neptis…… 2
Athyma… 3
Limenitis… 2
Euthalia… 2
Apatura… 1
Hestina… 1
Charaxes… 2
29
Nemeobiinæ  2 Zemeros… 1
Abisara… 1
 2
Lycænidæ… 21 Gerydus1
Neopithecops 1
Megisba… 1
Cyaniris… 1
Chilades… 1
Zizera… 2
Jamides… 1
Lampides… 1
Everes… 2
Nacaduba… 1
Catochrysops 2
Polyommatus 1
Arhopala… 2
Iraota… 1
Ilerda… 1
Pratapa… 1
Spindasis… 1
Tajuria… 2
Deudorix… 1
Lehera… 1
Rapala… 1
26
Pierinæ…  8 Delias…… 2
Prioneris… 1
Terias…… 2
Ixias… 1
Hebomoia… 1
Catopsilia… 2
Dercas… 1
Pieris…… 3
13
Papilioninæ  2 Papilio… 14
Leptocircus1
15
Hesperiidæ 21 Tagiades… 1
Odontoptilum1
Suastus… 1
Iambrix… 1
Hyarotis… 1
Matapa… 1
Erionota… 1
Taractrocera1
Ampittia… 1
Parnara… 5
Baoris… 3
Padraona… 1
Telicota… 1
Udaspes… 1
Halpe… 1
Astictopterus1
Kerana… 1
Notacrypta1
Hasora… 2
Badamia… 1
Ismene… 1
28
79 130

The species of Cyaniris was not observed before 1906, but was then fairly numerous in Hongkong Island, and will probably establish itself there.

Of the sixteen rare species, three belong to Danais and two to Euplœa, one each to Lethe, Melanitis, Cirrochroa, Cyrestis, Rhinopalpa, Hypolimnas, Curctis, Prioneris, Pieris, and two to Caprona.

There is a very well-marked wet and dry form in the case of many Hongkong butterflies (especially in the Satyrinæ, Precis, and Lycænidæ) and four cases of insects with dimorphic females—Cethosia biblis, having the commoner form of female like the male, chiefly of a brilliant orange-red on the upper side, relieved with black; whilst the second form of female is dark grey with black, brown, and white markings; the under side agrees in both forms in colour and markings. The other examples are Hypolimnos misippus, which is rare or sporadic; Papilio memnon, with its tailed and tailless females; and P. clytia; but in this latter case the dimorphism includes both sexes. Some of the butterflies, especially amongst the Euplœa and Satyrinæ, exhibit striking and numerous varieties—some of them doubtless incipient species, though, after all, even a species is but a very stable variety, and transitory like everything else. The swarms of Danais and Euplœa are curious here. These insects collect together in hundreds about the middle of the dry season (November–December) and cling on trees and bushes in sheltered localities, packed so closely that they hide much of the foliage, and darken the air in rising when disturbed. There are many interesting biological items in the history of Hongkong butterflies, but we have only space to mention a few:—Euthalia lubcutina lays a hemispherical egg, the peculiarity of which is the numerous glandular hairs on the upper surface, each hair with a little globule of brownish, viscous fluid at the tip; these are quite visible without a lens. The larva of Gerydus chinensis is of interest as feeding entirely on aphides; that of Spindasis lohita is one of the numerous instances of Lycænid larvæ being assiduously attended by ants, for the purpose of sipping the fluid exuded by the dorsal glands of the larva. Apparently the latter, in this case, is absolutely dependent for existence on the care and attention of the ants, and is usually to be found in their nests. These ants are a species of Cremastogaster. But there are some kinds of ants here which are inimical to the mature butterfly. These lie in wait amongst flowers and seize the butterfly by the proboscis as it feeds. A small pale yellow or while spider, with its legs tightly appressed to its body, likewise ambushes in flowers. In spite of its small size—about ¼-inch in diameter—it not only seizes, but sometimes manages to hold and kill, a large Papilio. This spider is almost indistinguishable amongst white or yellow blossoms. Besides the operations of the native woodcutters, which destroy many eggs and larvæ and tend to eradicate food plants, the increase of butterflies in South China is chiefly and to an enormous extent checked (especially amongst the Hesperiidæ) by egg and larva parasites, chiefly Hymenopterous, which are extremely numerous in South China. In the case of a moth, Metanestria punctata, whose larva feeds on fir-trees, and in certain years often defoliates large areas in China, examination of a great number of pupæ showed that fully 75 per cent. had been destroyed, chiefly by Dipterous and Hymenopterous parasites, whilst the eggs of the moth were heavily parasitised by Hymenoptera. No doubt these parasites always appear whenever the moth becomes very abundant. The insectivorous birds here destroy few mature butterflies, though they account for numbers of eggs, larvæ, and pupæ. I am, however, of opinion that on the whole the butterfly, having passed through manifold dangers in its immature stages, has few enemies in its adult state.

The geographical distribution of animals changes slowly in the natural course of things, but modern civilisation and constant and rapid communication with all parts of the world tends to effect some of these changes more rapidly, and, we may expect, will eventually cause many more species to become extinct and some almost cosmopolitan. Hongkong, as a focus for a continuous stream of traffic from near and distant countries, and, possessing a sub-tropical climate to which many animals and plants can adapt themselves, seems exceptionally well situated for observation of some of these phenomena, for exotic insects may be expected to occur frequently, and some of them to find a suitable habitat in the island. For many new plants have certainly been introduced or found their way lo Hongkong within the last fifty years, and some of them now flourish here; and butterflies, like man and most terrestrial animals are, directly or indirectly, dependent for existence on the vegetable kingdom. The small area of the island lends itself specially to the observation of the increase and decrease of native species, and the arrival of immigrants.

In conclusion, Hongkong possesses a very bright, varied, and individually numerous butterfly fauna, which enhances the beauty and life of the island even more than the birds which, with a few exceptions, are not particularly striking in plumage. At Foochow, about midway between Hongkong and Shanghai, the vegetation changes, and is, says Mr. S. T. Dunn, superintendent of the Afforestation Department at Hongkong, an almost equal intermingling of tropical and temperate forms. At Shanghai, about 900 miles north of Hongkong, so far as the vegetation is concerned, one might imagine oneself in England, and some of the commonest butterflies there are species of Colias and Goneptcryx, the familiar "Clouded Yellows" and "Brimstones"—typically Palæarctic genera.