BUTTERFLIES OF HONG KONG AND JAPAN. 205 



with Dr. Longstafi*. He puts forward the theory that butterflies 

 possibly orient themselves, or lie over sideways, in order to 

 escape detection. From observations I have made on many 

 hundreds of butterflies in South Africa, India, Malta, Mauritius, 

 Japan, and South China, I am convinced that the so-called 

 orientatation, or lying sideways, is only done in order to enable 

 the sun to warm an additional wing area. A large number of 

 butterflies orient themselves roughly towards sundown, and open 

 their wings for the very obvious purpose of getting the warmth 

 from the sun as it gets lower down in the heavens. Even 

 " swallowtails " of various kinds do it, and I have seen P. rapce 

 do it in Malta. The most obvious cases of inclining sideways 

 for purposes of warmth were two I noticed in Hong Kong on two 

 separate days in December last. The weather was bright and 

 sunny, but a cold east wind was blowing, cold, that is to say, for 

 the Tropics, and few butterflies were about. On each occasion 

 the butterfly under observation was a Catopsilia pomona, one a 

 male, and the other a female. Now C. pomona, ordinarily, is a 

 very rapid flyer, and when it settles it does so suddenly, with a 

 snap of the wings as it were, and when it does settle it is 

 generally almost impossible to see, as it closes its wings on its 

 back and remains perfectly upright. However, on each of the 

 two occasions now mentioned the butterflies inclined sideways, 

 so that the wings nearest the sun were at right angles to its 

 beams. As the season was not the usual time when C. pomona 

 is out, and the day was unusually chilly, obviously the butter- 

 flies had inclined sideways for warmth and not for concealment. 

 The result was, that instead of the butterflies being invisible 

 when at rest, the moment they inclined over to the angle of 45° 

 they became visible on the foliage at a distance of over fifty 

 yards as bright yellow spots. The question of lessened shadows, 

 as mentioned on page 551 of Dr. Longstaffs book, could not 

 possibly arise as a means of protection. A bird would have 

 made a bee-line for the yellow spots representing the butterflies, 

 and the shadows would not have been seen until the bird, or the 

 observer, was almost touching the butterflies. 



Last summer, 1912, I managed to get in two months' leave 

 to Japan. Considering the heat of the climate in July and 

 August, and the luxuriance of the vegetation, I was disappointed 

 on the whole with the butterfly fauna. I managed, however, to 

 take some fifty odd species of butterflies which I wanted, and 

 managed to get a good series of each. Among my best captures 

 were P. bianor var. maacki. These splendid butterflies were 

 of two different types, some having metallic green markings 

 others metallic blue markings The blue varieties are very 

 fine to look at. The most local insect was Lethe callipteris, 

 which I only found in the woods round Lake Chuzenji, above 

 Nikko, some 4000 ft. up. Here it was quite common. In 



