Sonic hreeding experiments on Catopsilia lyyranthc. 705 



tlicy liy with great rapidity, and can give points to Colias 

 edusa. Tiiey select the sea-coast, I feel sure, simply to 

 avoid obstacles. The road between Trincomalee and 

 Kandy, which runs through dense forest, is also largely 

 used by the migrating insects. When travelling south 

 they have the N.E. monsoon behind them, but when 

 turning north they meet a stiff wind which really seems 

 to drive them to a faster Hight. The breadth of the 

 flight is usually not more than a quarter of a mile. 



The cross-barred line on the map shows one of the 

 lines of migration of the two species of Ajjpias, Paulina 

 and Albina. They both breed in the low country, as 

 shown by the square dots, and fly in a broad belt of 

 insects about a quarter of a mile wide across the open 

 downs at D'lawa, 4,000 feet, and up to the Horton Plains, 

 7,000 feet, when they turn north toward N'Eliya, 6,000 

 feet, cross the plateau towards Rambodde Pass at its 

 northern end, and then make their way again to the low 

 country somwliere near Kandy. Part of the flight edges 

 away across the D'lawa Downs northwards and reaches the 

 N'Eliya plateau through the Hakgala Pass. 



The migration of Euploia montana starts somewhere in 

 the neighbourhood of the Hortons, and follows much the 

 same course, so far as I know, as Appias. 



The uninterrupted line is a curious and interesting one ; 

 it is that of Kallima jjhilarclius, which annually migrates, 

 sometimes in large numbers, though it is usually considered 

 a rare insect. So far as I can at present ascertain there 

 is only one migration annually in November or early in 

 December. The insects come up from the low country to 

 Haldumulle, then up the passes leading to the Hortons, 

 and then across the plains to some uncertain locality, but 

 where I have no idea. The insect does not occur in the 

 Colombo or immediate Kandy districts nor about N'Eliya. 



It is extremely difficult to obtain assistance in carrying 

 out an investigation such as this requires. Entomologists 

 are few in number, and, with the exception of Trincomalee 

 and one or two other places, Europeans are confined to 

 Colombo and the Hill district. The remainder of the 

 island is mostly covered with jungle, is thinly inhabited 

 with only here and there a few overworked Government 

 officials and ignorant natives. 



The reason for these flights is at present very obscure ; 

 it was probably originally a question of food-supply. This 



