THE HATRSTBEAKS, COPPERS AND HLUES 185 



The eggs are laid on the twigs of these trees late in the summer, 

 and the young caterpillars do not appear till the following spring. 

 The chrysalis may be found attached to an elm twig or leaf about 

 the end of June. 



The caterpillar is pale green. The ridges along the back are 

 tinged with yellow, and there are tw 7 o fine oblique white lines on each 

 side of each segment. 



The Dark HairstreaTc (Thecla Pruni) 



The upper side of this butterfly is very much like that of 

 W-album, but it may be distinguished by the presence of a few 

 orange spots near the anal angle of the hind wings. The colouring 

 of the under side (Plate VI, fig. 5) is also very similar, except that 

 the white lines of the wings are thinner and less distinct than in the 

 last species, and do not exhibit the W-shaped bend. The orange 

 band of this surface is bordered on each side with a row of black 

 spots, each of which is touched with a bluish white or a metallic 

 blue. 



This insect is not by any means common, but has been seen in 

 considerable numbers in certain localities. It is not found in 

 either Scotland or Ireland, and its chief haunts in England seem 

 to be in Huntingdonshire, Cambridgeshire and Northamptonshire. 

 It frequents wooded country, and flies during June and July. 



The eggs are laid late in the summer on the twigs of the black- 

 thorn (Prunus spinosa), and are not hatched till the following 

 spring. 



The caterpillar, which is pale green, with rows of yellow spots, 

 may be found in May. 



The Purple Hair streak (Thecla Quercusj 



This pretty butterfly, by far the commonest of the Hairstreaks, 

 though comparatively very small, reminds one forcibly of the noble 

 Purple Emperor. Its haunts are the same oak woods, and its upper 

 surface, though only a dull dark brown in certain lights, exhibits 

 the same imperial purple reflections when viewed at certain angles. 

 The purple of the male extends over the whole of the wings, but 

 that of the female is confined to a V-shaped patch at the base of 

 the fore wings. In the latter case, however, the purple is much 

 richer than in the male sex. 



