IV 
PREFATORY NOTE. 
to destroy the trees with impunity. The island is not, therefore, a fair sample of the vegetation of 
S. China, such as the mainland opposite presents. Macao is about forty miles west and slightly 
south of Hongkong, on the opposite side of the West River estuary, occupying a tiny peninsula of 
the district of Heungshan, one of a series of islands lying in the estuary and only separated from 
each other and the mainland by very narrow channels. The country near both places is very hilly 
but few summits attain three thousand feet, and the hills lie in confused masses rather than distinct 
ranges. The geological formation is igneous and for the most part a grey granite. 
The summer is hot and moist; the winter or dry season usually hot during the day, but 
with short spells, generally in January and February, of really cold weather, sunless and often with 
dense fog or drizzling mist. The wet and dry seasons are well differentiated and many butterflies 
have their very distinct seasonal forms, whilst the majority vary slightly at each period. Through 
the courtesy of Mr. Figg of the Kowloon Observatory I am able to give the following climatic 
notes for the twenty years 1884-1903 inclusive. Taking October to March inclusive as the dry 
season, for the rainfall seems to diminish rapidly in October and rise correspondingly in April, the 
mean six months rainfall is 13.28 inches ; the mean six months wet season 71.54 inches. The mean 
annual rainfall is therefore 84.82 inches. The lowest temperature occurring during these twenty 
years was 32 0 F. in January 1893 ; the highest 97 0 in August 1900. The two coolest months are 
January and February with a mean temp, of 58.7 F. The weather during these months is extremely 
variable; during February 1905 the therm, on the tenth fell to 42.8° and a few days later rose to 
73 * 5 °* Violent rain accompanies the typhoons which frequently occur, generally during July, 
August or September, but it does not appear to destroy much insect life, butterflies being as 
numerous as usual a day or two after one of these storms. A long-continued spell of cold weather, 
however, will make butterflies very scarce for weeks after. But probably the chief reason why some 
butterflies are very sporadic in their appearance here, abundant some years and then missing for 
several years, is the continual destruction of the foodplants of larvae by the native fuel-gatherers, 
whilst the flocks of goats seem to be increasing, animals most destructive to plants and young trees ; 
and the great numbers of pigs which roam through the woods must nearly exterminate some plants. 
Some excellent reasons why butterflies are such an interesting study and especially 
valuable in solving many problems in nature, may be found in the address to the Ent. Soc. of London 
for 1903, Part V, entitled “What is a Species?” and a few passages are here quoted. Insects are 
valuable as a study because of c£ the large number of offspring produced by each pair of insects, and 
the rapidity with which the generations succeed each other, many cycles being completed in a single 
year in warm countries ; in the severity of the struggle for life which prevents this remarkable rate 
of multiplication from becoming the cause of any progressive increase in the number of individuals; 
and finally, in the character of the struggle itself, which is precisely of that highly specialized kind 
between the keen senses and activities of enemies, and the means of concealment or other modes of 
defence of their insect prey, which leads, by action and reaction, to a progressive raising of the 
standard in both pursuer and pursued.” And further on “they (butterflies) stand at the head, not 
