THE BLACK HAIRSTREAK. 143 



The Black Hairstreak (Thecla pruni). 



This butterfly is figured on Plate 96. In colour it is dark 

 brown or, when quite fresh, brownish-black ; there are some 

 orange marks on the outer margin of the hind wings, and these 

 are most distinct in the female, in which sex there are orange 

 spots on the fore wings also. The male has a pale sexual mark 

 at the end of the cell of the fore wings, but this is less distinct 

 than in the following species. The under side is brown, with a 

 bluish-white interrupted transverse line on each wing, that on 

 the hind wings angled before reaching the inner margin. All 

 the wings have an orange band on the outer margin, but on the 

 fore wings of the male this is often indistinct ; there are some 

 white-edged black spots before it, and, on the hind wings, 

 beyond it also. 



The eggs are laid in July on the twigs of blackthorn, but the 

 caterpillars do not hatch until the following spring. The egg 

 figured on Plate 97 was reddish-brown and appeared rather 

 shiny. The caterpillar is described as yellowish-green, with a 

 darker green furrow and purplish ridges along the back ; the 

 latter are edged with whitish and the divisions between the 

 rings are yellowish. The head is pale brown. The chrysalis, 

 which is attached by the tail and has a silken thread around it, 

 is black, marked on the head and body with yellowish-white. 



The caterpillars feed on blackthorn (Primus spinosa) in a 

 state of nature, but will eat the leaves of damson in confinement. 

 They may be obtained in May, in their particular haunts, by 

 beating sloe bushes with a beating tray, or an inverted open 

 umbrella, held under to intercept the evicted caterpillars, etc. 



This butterfly was not known as British until 1828, when 

 a number of specimens were captured at Monkswood in 

 Huntingdonshire. These were sold by the captor as T. 

 w-album, which was then called the Black Hairstreak. As 

 soon as the mistake was detected, it was given out that the 



