MIGRATION AND DISPERS.VL OP INSECTS — LEPIDOPTERA. 99 



of these white butterflies may be seen qiienchinp; their thirst on the 

 <lamp ground or flying up when disturbed in quite a startling cloud." 



The periodical flights of butterflies in Ceylon appear to take place 

 in April, shortly before the S.W. monsoon, and again in the middle of 

 November. According to Holdsworth {Field, June 29th, 1872) the 

 flight may be observed each year at Colombo in November, from south 

 to north, whilst according to Radley (Entotnnliniist, xxvi., p. 134) the 

 flights in spring are from north to south. The latter says that the 

 spring flights " usually occur shortly before the S.W. monsoon (about 

 April). Occasionally, owing to cyclones in the Bay of Bengal, there 

 are a few fine l)ut very cold days during the wettest months of IJecember 

 and January, and then a small flight takes place, but during the big 

 flight (April), which lasts about a week, the butterflies pass in millions, 

 and for one or two days you can almost imagine that it is snowing, so 

 thickly do they come. This flight is largely composed of Cntupsilia 

 catilla, und ('. crocalc Avith ('. jujrmitlii', Catoji/iai/a jiroiiihu and C. (jalcnr 

 in fewer numbers. Large flights of hcuiiia ascla, usually accompanied 

 by Paralitica ccijlonica, have also been observed in February." Radley 

 further notes that large flights of yellow butterflies have been observed 

 at sea, out of sight of land, ott' the coast of India and Ceylon, that he 

 himself has noticed, when out dredging, haiuia asda flying out to sea, and 

 when going to the Maldive Islands, in 1892, he saw two of the same 

 species about 100 miles from the Maldives, that must have come from 

 Ceylon and against the wind. Holdsworth observes that in November, 

 most of the flights consist of white and yellow species, but also a great 

 number of I'aiiiHo Jiertov, and msinj oi Ornithoptrra danitis and that these 

 flights almost invariably travel against the wind, the N.E. monsoon 

 setting in early in November. Holdsworth adds that he believes there is a 

 regular migration of /'. hcctnv horn India to the north-west of Ceylon, 

 that from the middle of February to the middle of April, he was usually 

 at sea cruising in the neighbourhood of the Pearl Banks, that during 

 three seasons he saw, at a distance of from ten to sixteen miles from 

 the land, straggling parties of P. licctor flying low and steadily towards 

 the coast of Ceylon, in a direction nearly due east. They were more 

 usually observed at the end of February, at the beginning of the short, 

 calm season between the monsoons, the distance from India to the 

 part of Ceylon to which these hundreds of butterflies were making 

 being not less than sixty miles. Moss criticised {The Field) Holds- 

 worth's statement that the flights of these migrating butterflies were 

 against the wind, but Holdsworth [Iih-. rit., December 28th) maintained 

 his position, and notices that, on December 3rd, 1805, the Galle Face 

 was almost overshadowed by a great cloud of yellow and white butter- 

 flies, flying in the direction of the port and making fair but unsteady 

 progress against the N.E. monsoon, and he adds that, at the Galle Face 

 Hotel, he has seen " scores of PajiilioJiectdr and Oniitlioptera darsiiis in 

 company with numbers of the smaller yellow and white species, 

 struggling successfully to make head against the longshore wind, many 

 of them keeping outside the belt of cocoa-nut trees and flying low 

 and close to the beach." 'Slaim observes {ZtJoL, 1895, p. 335) that in 

 Ceylon there is, in March and April, a vast migration of ( 'at<ij>li<(ii(i 

 (jalene, I\ld., from north-east to south-west, they appear not merely in 

 hundreds, but in thousands, perhaps millions. The movement of 

 countless numbers all going in one direction as of set purpose, was first 



