NOTES ON THE LIFE-HISTORY OF COLIAS NASTES. 123 



23rd, of a pale straw-colour, and had evidently only just been 

 deposited ; the larva emerged on July 5th. 



The newly emerged larva is barely a millimetre in length ; it 

 is of brownish green colour, with head black and shining. _ It 

 is covered with tubercles, each tubercle emitting a white spine. 

 I at once placed it upon a leaf of Astragalus, on which it com- 

 menced to feed, forming a small semicircular notch on the edge, 

 and then stretched itself out at full length on the upper surface 

 of the midrib of the leaflet. 



On July 6th the larva had fed during the preceding night, 

 which, it must be remembered, was as light as at noon; it 

 remained during the day stretched out as before. 



On July 7th the larva had not fed or moved, but after this 

 day, until July 12tb, it fed slowly, eating round holes in the 

 leaflet, always from the upper side ; when moved to change the 

 food, which had to be done daily, the larva invariably stretched 

 itself on the upper side of the midrib of a leaflet. From 

 July 12th to the 16th it remained quiescent ; on the latter day 

 the change into the second instar occurred. It was_ during 

 this stage of practically the same appearance as during the 

 previous instar, except that on the 16th its length had increased 

 to 2 millim. 



From July 18th to 28th I was travelling to England, and 

 could thus only imperfectly observe the progress. By the time 

 I had reached Christiania, on July 24th, the plants of Astragalus 

 I had brought from Abisko were yellow and unfit for food. I was 

 therefore forced to attempt to discover a substitute. The only 

 leguminous plant I could find was the common white clover, 

 Trifolium repens, which fortunately the larva took to quite 

 naturally, and upon which it fed freely thereafter. 



On July 31st the larva changed into the third instar. On 

 August 2nd it was 5 millim. long ; the head was light yellowish 

 green, thickly studded with tubercles, each of which emitted a 

 black spine; the remainder of the segments were dull green, 

 with faint darker dorsal and subdorsal lines and light spiracular 

 stripes. The whole of this area was thickly covered with white 

 tubercles, each emitting a short spine. The ventral area was 

 of the same tone of green as the dorsal. During this stage 

 the larva fed chiefly on the upper epidermis of the clover- 

 leaves, and hung by a thread when shook off. 



On August 5th it ceased feeding, and prepared to change into 

 the next stage. On the morning of August 6th I found it had 

 changed during the night into the fourth instar. It was then 

 6 millim. long, of a decidedly darker colour than in the preceding 

 instars, with the dark dorsal line not so apparent ; the sub- 

 dorsal lines were now light coloured, almost as light as the 

 spiracular line, which itself was much lighter than in the pre- 

 ceding stages ; the head was light green, as in the last stage ; 



