184 BRITISH BUTTERFLIES 



white lines, the inner one of which is indistinct ; and on the hind 

 wings are two others, the outer one being longer and more distinct 

 than the inner. 



This butterfly is by no means an abundant insect, though it is 

 widely distributed, and in some places 

 plentiful. Its chief haunts are woods, 

 and we may mention among its 

 favoured localities Epping Forest, 

 Monk's Wood in Cambridgeshire, the 

 wooded parts of South Devon and 

 Dorset, New Forest, Colchester, and 

 Peterborough. 



The perfect insect is 011 the wing 

 FIG. 83. THE BROWN HAIR- from July to October, and the eggs are 

 STREAK MALE. deposited in the autumn on the twigs 



of its food plant the blackthorn 



(Prunus spinosa). These do not hatch till the following spring. 

 Toward the end of June the caterpillar is fully fed. 



The colour of the caterpillar is light green, with two white stripes 

 down the back, and two others along the sides. There are also two 

 small oblique whitish lines on each side of each segment. 

 The chrysalis is smooth, and of a pale brown colour. 



The Black Hairstreak, or White-letter Hair streak 

 (Thecla W- album) 



The first of the above two popular names has been applied to 



this species on account of the very deep brown colour of the upper 



side, which colour is often a near approach 



. |^^^ v / ^&& to kl ac k' The secon d i s due to the W-shaped 



Bs^ji>^|B| bend of the white streak of the hind wings. 



mm The ground colour of the under side (Plate 



VI, fig, 4) is greyish brown, with a bright 



orange band, spotted with black near the 



hind margin of the hind wings. 



FIG. 84. THE WHITE- W-album is a somewhat rare insect, but 



LETTER HAIRSTREAK. is occasionally seen in plenty in a few loca- 

 lities, Cambridgeshire, Berkshire, Epping, 



Colchester and Suffolk being among its chief resorts. It is out 

 on the wing in July, and should be looked for in wooded country 

 where the common elm (Ulmus campestris) and the wych elm 

 (U. montana), its food plants, exist. 



