Illi: MICIiATloNS or lU'l IKKKLIES. 1085 



... I >tu)ulil roiiiiiik Hint iiiiKPii^.sl tlir iiiiiiii hdily of tliesi> travelling white l)utterflies, 

 smiill j;roii|>s of lialf-n-ilo/.cii iiuliviiliiiils oi- iiiori'. miiy bt observed, wliicli in strings 

 of sciinenco, lookinf; iis if playinL; ■follow my leader," have a pretty appearance. In 

 some portions of tlio conntry in tlieir line of Miirlit. where shallow water may be 

 lying, large nnmbers of these white butlerllies may be seen iiuenching their thirst on 

 the damp gronnd, and (lying up when distnrbeil, in (jnite a startling cloud. (Moore, 

 Lep. Ceylon, i: 11(!-117.) 



Tcnuant in Iiis Ceylon also tells nt" "Hifrhts of tlicse ilclieatc ereatures, 

 generally of a wliitc or j)ale yellow hue, apparently miles in breadth, and 

 of siieh prodigious extension as to oeciipy hours and even days, uninter- 

 ruptcdlv in their passage." Spriiee also tells of a "vast multitude of 

 butterliies" of "eommon white and orange yellow s})eeies," Hying to the 

 S. S. E. across the Amazon at right angles to the wind in November, 1849. 



Mackwood (Moore, Butt. Ceylon) states that the species of Catophaga 

 take part in the "large annual flights" of butterflies in the early months of 

 the year, a few weeks after which C. laidvapura may "be found congre- 

 gated on damp spots in the open sunshine in great nund)ers ; I have seen 

 quite one hundred within the diameter of twelve inches." 



The immense numbers of Aporia crutaegi of Europe which at Easter, 

 1829, made the thorn trees on the promenade at Erfurt look as if hung 

 with white blossoms has been related by Keferstein ; and the sudden out- 

 burst of Ncophasia mcnapia in Washington Territory in 1882 was, accord- 

 ing to Hagen, "wonderful and indeed only to be compared with an 

 irruption." 



But besides this mere thronging found in the temperate zone, there are 

 known examples among the Pieridi of actual migi-ations. The late 

 Mr. W. W. Hill of Albany spent the month of April 1884 on the 

 Indian River, Florida, and wrote me concerning the movements of Ascia 

 monuste : — 



During the last ten days of my stay there I observed that Pieris monuste seemed 

 impelled to move southward. At first there were but few of them to be seen but their 

 numbers steadily increased until at the end of ten days, when the time came for me 

 to make my departure, many hundreds could be seen at any one time during the day, 

 when not stopping momentarily at some bed of flowers, moving in one direction. If 

 obstructions were encountered, these butterflies Hew over or around them and kept 

 on In the same southerly direction. 



We have also already recorded (p. 378) a flight of Pieris rapae, and 

 others might be given from the collections made by Cornelius, Keferstein 

 and Werneburg. Its near ally and fellow vagrant of Europe, Mancip- 

 ium brassicae, has also been noticed moving in streams as it were ; thus 

 F. Schmidt crossed a swarm in flight on a calm day and estimated that it 

 was a kilometer wide moving in a southerly direction away from the sea 

 near which the observation was made ; on enquiry of others he learned 

 that it had lasted all day and had been seen from a vessel seven and eight 

 miles from land, having, he conjectured , come from an island to the north. 



