116 THE LEPIDOPTERA OF CEYLON. 



NILASERA PIEAMA (Plate 43, Fig. 3, Za,b, $ 9, 3c, larva). 



Male. Upperside brilliant ultramarine- blue ; both wings with marginal black 

 band. Female purplish-blue, merging to greyish-blue at the base ; marginal bands 

 broad. Underside brown, suffused with purple-grey : forewing with slender white- 

 bordered discoidal marks, less defined discal band, streaks below the cell, and 

 submarginal fascige : hindwing with very indistinct browner basal spots, discal band, 

 and submarginal lunular line ; a few green speckles above anal angle. 



Expanse Ittj inch. 



Larva elongated, oval, depressed, anterior segment scutate ; finely pilose along 

 the sides ; colour green, with dorsal and lateral reddish marks, and an intervening 

 subdorsal slender black line. Pupa green ; dorsal segments reddish. 



" Feeds on Schleichera trijuga " (Thwaites). 



Is nearest allied to the Javan N. pseudocentaurus, and is quite distinct from both 

 the Indian N. Gentaurus, and the Malayan N. Nakula. 



" Kandy and GaEe. Common ; but settles rather high" {Wade). 

 " Colombo, and low country" (Machwood). 



Family PAPILIONID.a;. 



Six perfect legs in both sexes. Pupa secured by the tail and a girdle across, 

 the middle. 



Subfamily PIERIN.^. 



Abdominal margin of the hindwing not curved inwards. 



" This family of butterflies contains several species which are remarkable, like 

 some of the Buploein^, for their apparently migratory flights. In the Pieringe, how- 

 ever, these flights are still more extraordinary. At certain times of the year immense 

 hosts of these butterflies, mostly of a white colour or nearly white, may be observed 

 during the hottest part of the day rushing in an impetuous flight across the country, 

 driven by some irresistible instinctive impulse, and impatient of any obstruction in 

 their headlong course ; even ascending hills of 6000 feet in elevation, and descending 

 again ; striking like animated snow-flakes against any one meeting them in their 

 course and then, after passing the obstruction, making on with the same pertinacity 

 as before, towards where they are hurrying to, until the failure of sunshine arrests 

 their progress for the day ; to be continued probably on succeeding days until the 



