Some hreeding experiments on Catopsilia pyranthc. 703 



The results of these experiments are very meagre, only 

 about fifteen to twenty specimens coming to maturity out 

 of quite 200 larvaj. It shows that the constitution of the 

 larvae is somewhat delicate.* 



I mentioned above that Mr. Wickwar had found tliat 

 75 per cent, of the insects captured during the dry February 

 flight were males, and quite independently we had observed 

 that the wet-season flight in November and December 

 were almost all females. I cannot account for this further 

 than to say that possibly during the dry months, owing to 

 a more scanty and drier foliage, the female larvae, if I may 

 use the expression, succumbed ; whereas with the damper 

 and more luscious foliage of the wet months they had no 

 difficulty in surviving. The mystery of these migrations 

 may be explained to some extent by this preponderance 

 of the sexes during the different flights. 



By a coincidence a migratory flight of butterflies was 

 in full swing on the day I landed in Ceylon, October 25, 

 1895, and I certainly thought that I had stepped into a 

 land of butterflies. The harbour, streets, and large pro- 

 menade, the Galle Face by the sea-shore, was alive with 

 butterflies, and being mostly composed of Gatopsilias, 

 looked for all the world like a snow-storm. In order to 

 gain some idea of their numbers, I selected two points, 

 one at the edge of the sea and the other twenty yards 

 from it, and then counted them as they flew past. The 

 result of my calculation and that of my companion taken 

 separately gave fourteen thousand insects between 10 a.m. 

 and 2 p.m. The flight usually lasts about a week ; we 

 have therefore ninety-eight thousand butterflies passing 

 through a space sixty feet broad in twenty-eight hours. 

 In round numbers 100,000. 



The sketch map of Ceylon (Plate XXXV) gives the 

 course of these migrations which I have personally 

 observed during the time I was in the island. 



There is a distinct difference in procedure between a 

 migratory swarm of butterflies and a swarm of locusts. 

 I mean that the latter advance like a human army so 

 many miles a day from one point to another, and the 



* The larvse were collected in my garden in Colombo, i. e. at sea- 

 level ; and all, or the very great majority, in the .'^ame week ; and 

 all from the same food-plants. A considerable number of the eggs 

 were laid by the same female. I used to follow her when she was 

 ovipositing, and snipped off the leaf on which the egg was laid. 



