tlie Life History of Agriades thersites. 287 



One conclusion arrived at was to confirm the idea that 

 the food-plant of A. thersites was Onobrychis (Sainfoin) in 

 its cultivated and wild and alpine forms. The butterfly 

 was seen to lay on it; it was most numerous wherei the 

 plant grew wild in some quantity, and though it was not 

 found everywhere where Sainfoin was seen, it was never 

 met with where Sainfoin was absent. Quite possibly it 

 has other food- plants, but the observations not only gave 

 no indication of what they might be, but tempted one to 

 the conclusion that it had no food-plant but Sainfoin. 

 This conclusion is certainly correct for the portions of 

 Dauphiny explored, but there may, in other areas, be some 

 equally acceptable plant that does not occur in these valleys. 



The other conclusion arrived at is that A. thersites is 

 double-brooded throughout most of its range, but at Le 

 Lautaret it is single-brooded. It was certainly somewhat 

 of a surprise to find the butterfly at Le Lautaret as high 

 as 7500 ft., and a specimen or two even higher. The dates 

 of appearance were only explicable on the idea of a single 

 brood, as the species at 7000 ft. was going over before the 

 second brood at 2500 ft. was fully out. At Le Lautaret 

 the butterflies were contemporaneous with the flowering 

 of the Sainfoin, as was probably the first brood at the 

 lower level, the second brood coming out, when the second 

 crop of Sainfoin (where cultivated) was nearly ready for 

 cutting. 



The specimens, single-brooded from Lautaret, and 

 second-brooded from Bourg d'Oisans, flying at the same 

 date, but with a difference in the elevation of their habitats 

 of 5000 ft. did not in the field, nor do they now in my 

 boxes, present any differences that I can detect, they are 

 about the same size. A few measured, selected as large 

 or small, varied (^(^ 30-43 mm. at Bourg d'Oisans, 29- 

 35 mm. at Lautaret, but these Lautaret specimens were 

 (accidentally) exceptional. The $ $ at Bourg 27-35 mm., 

 at Lautaret 29-31 mm. The mass of specimens were 

 between these extremes — about 33 mm. (^(^, 32 mm. $$ 

 at both places. 



At Bourg d'Oisans A. thersites occurred up to about 

 4000 ft. (still in second brood) in warm corners on the 

 sunny side of the valley, but, though one can by no means 

 be certain, I don't think it occurred at elevations inter- 

 mediate between this and the single-brooded high level 

 (6500 ft.). 



