Some breeding experiments on Catopsilia pyranthe. 703 
The results of these experiments are very meagre, only 
about fifteen to twenty specimens coming to maturity out 
of quite 200 larve. It shows that the constitution of the 
larve is somewhat delicate.* 
I mentioned above that Mr. Wickwar had found that 
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 im 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 larve, 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 Catopsilias, 
looked for all the world lke 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 nimety-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 ditference 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 larve were collected in my garden in Colombo, 7. ¢. at sea- 
level ; and all, or the very great majority, in the same 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. 
