192 BRITISH BUTTERFLIES 



with a border of reddish spots, and a number of black spots in white 

 rings, the arrangement of which is here represented. 



The butterfly frequents chalky downs, chiefly in the south of 

 England, and seems to be unknown in Scotland and Ireland. The 

 Isle of Wight, and the chalky downs and banks of Sussex, Surrey, 

 and Kent, are its favourite localities ; and even in these it is generally 

 very local, sometimes swarming on a grassy bank of no great extent, 

 when the surrounding neighbourhood, though apparently equally 

 suitable to its requirements, does not harbour a single specimen. 

 It is on the wing in May and June, and again in August. 



The caterpillar is green, with two rows of yellow streaks on the 

 back, and a yellow stripe on each side. It feeds on the Dutch clover 

 (Trifolium repens), horse -shoe vetch (Hippocrepis comosa), and 

 various other leguminous plants. 



The Chalk-Hill Blue (Lyccena Corydon) 



The male of this species (Plate VII, fig. 1) is readily to be dis- 

 tinguished from all other members of the genus by its pale glossy 

 blue, but the female (fig. 2 of Plate VII) so closely resembles that 

 of Bellargus that it is often a somewhat difficult matter to dis- 

 criminate between them. The following, however, are a few points 



worthy of observation : The upper 

 side of the female Corydon has the 

 bases of the wings more or less 

 s prinkled with the pale silky blue that 

 characterises the male ; and the black 

 bars of the fringe are usually broader 

 in Corydon than in Bellargus. The 

 black-centred spots of the under side 

 F IG . 91. _THE CHALK HILL ar e also usually more conspicuous in 

 BLUE UNDER SIDE. the former species than in the latter. 



The difficulty of identification is 



increased by the fact that both these butterflies frequent similar 

 localities, and are often on the wing at the same time; but al- 

 though Corydon is certainly a frequenter of chalky districts, yet it 

 is often found plentifully in districts far removed from the chalk, 

 notably at Arnside in Lancashire, and in Epping Poorest. 



The butterfly is out in June and July. The caterpillar is green, 

 with two rows of short yellow streaks on the back, and a yellow 

 stripe on each side. It feeds on the purple and Dutch clovers 



