194 THE BUTTERFLIES OF THE BRITISH ISLES. 



The males vary a little in the width of the marginal border, 

 and in some females there is almost as much fulvous on the 

 discal area of the wings as in the male ; in the darkest females 

 the spots always appear paler than in fulvous specimens. On 

 the under side the ground colour is sometimes olive-brown 

 rather than green. 



The following account of the life-history of this butterfly is 

 adapted from Mr. Frohawk's article on the subject published in 

 the Entomologist for 1901 : — 



In August, whilst watching some of the butterflies on the 

 wing over a patch of chalky ground covered with a short dense 

 growth of various grasses, etc., he noted a female hovering 

 close over the plants. Presently it settled on a tuft of hair grass 

 (Aira cozspitosd), and after walking over and among it a little 

 time, she curved her abdomen down, and deposited a single 

 egg on one of the fine hair-like blades, or, rather, spines, and 

 close by, within an inch, another egg was found. Afterwards 

 some plants of this grass were potted up, and some females 

 placed on them. These deposited a large number of eggs 

 upon the grass-stems and blades. 



The egg when newly laid is pearl white with the slightest 

 yellowish-green tinge, which very gradually turns deeper in 

 colour, assuming a pale straw-yellow on the sixth day, and so 

 it remains until January, when it becomes paler. 



The caterpillar hatches out at the end of March or early in 

 April. It does not eat the empty egg-shell, but directly after 

 leaving the egg it starts spinning the fine grass together into 

 a somewhat dense cluster an inch or two above the ground. 

 In this compact shelter the larva lives and feeds upon the grass 

 surrounding it, remaining almost always completely hidden. 

 Sometimes as many as three or four live together. When full 

 grown and about one hundred days old, the caterpillar is of a 

 dull olive-green colour, with a black collar on the first ring, and 

 the entire surface densely sprinkled with minute shining black 



