24 [January, 1914. 



The pupa varies a little in tint, usually the thorax and wing cases are 

 bright green, the abdomen ochreous ; there is a faint dorsal line (darker) and 

 numerous minute hairs. Length, 9 - 5 mm., greatest width, 3 - l mm. There is 

 the usual waist at first abdominal segment. The summit of meso-thorax is 

 rather high, so that this point is as high as at 3rd abdominal segment. Seen 

 from above, the pupa narrows forward from the abdomen. It is quite free, 

 though it sometimes adheres to the larva skin, and the latter again to some 

 surface. There is no silken pad nor any trace of girth or cocoon. 



My first acquaintance with the larva of P. argyrognomon in its 

 association with ants was in Carinthia in 1897, when I found a few 

 larvae on Vicia lutea. The larvae themselves on the plant, some ten to 

 twenty inches from the ground, would have been very inconspicuous, 

 but each was easily found by its being attended by several black ants 

 (Formica fusca ?) , which made an easily seen black point. 



In the Val Veni (above Courmayeur), at about 5,000 feet, and 

 about a mile below the Chalet de l'Avizaille, is a rather barren flat, 

 long left by the stream, with stunted spruce and larch ; on the inter- 

 vening spaces is a rather scattered vegetation, including Sainfoin, 

 Helianthemum, Anthyilis, Hippocrepis, etc., etc. The Sainfoin, much 

 less luxuriant than that of the hayfields below, has nearly all the leaves 

 direct from the root-stock, and the flowering-stems are short with one 

 spike and a leaf or two. The leaves of some of these were seen to 

 have been eaten, usually shown by white patches where one cuticle was 

 left uneaten. On searching at the base of these, Lycwna larvae were 

 found which proved to be those of P. argyrognomon. Further search 

 showed them to be usually on the stem close to the root-stock, but 

 occasionally on the leaves. It was notable that the inhabited plants were 

 in little groups, with often considerable spaces between in Which all the 

 plants were healthy and unaffected. The " healthy " plants were 

 amongst a good deal of other vegetation, largely moss, giving a green, 

 smooth surface to the ground. The affected plants were in coarse sand 

 instead of moss. This sand was in reality material brought up to the 

 surface by a small black ant {Formica fusca), and then scattered about 

 the plants, though before this was fully appreciated, it had become only 

 too evident that the plants with larvae were well patrolled by these ants, 

 as they rapidly got all over one, their crawling being rather annoying, 

 apart from occasional sharp, but not very severe bites. Though the 

 ants were everywhere, they were only in force near the affected plants, 

 which seemed as a rule to be close to or actually on their nests, so that 

 they appeared abundantly as soon as the affected plants were touched. 



