138 LEPIDOPTERA. 



changes, ay regards the ocellated spots, are produced by in- 

 sufficient food, and there can be no doubt that the thin and 

 imperfect colouring is attributable to the same cause. 



On the wing in August and September, and, after hyberna- 

 tion, in April and May. 



Larva, 1 1 inch long, somewhat cylindrical ; head rather 

 large,- hairy, shining black ; second and anal segments 

 also shining black ; body velvety black with transverse rows 

 of white dots on each segment; segments 3 to 12 set with 

 very numerous black branched spines; legs black; pro-legs 

 purplish-black, with the feet paler. When young the spines 

 are much shorter, the body of a dingy brown, the interstices 

 of the segments reddish, and the white spots very indistinct, 

 or hardly indicated. 



On Urtica dioica (nettle), gregariously on the tops, and 

 forming a considerable web. June and July. 



Pupa stout, dorsal outline rounded, with a hollow behind 

 the thorax ; head with two prominent divergent spikes or 

 points ; a short spike or point at the back of the thorax, 

 another at the shoulder of each wing sheath, another at the 

 edge of each wing case, and a row of six on each side of the 

 back of the abdominal segments. Colour extremely variable — 

 greenish-yellow, pale grey, pale brown, smoky-brown, or 

 grey dusted with smoky, the colours being apparently affected 

 by the substance upon which it spins up. Metallic-golden 

 spots show themselves on the back of the abdominal segments 

 and sometimes upon the thorax. 



Reaumur showed that this metallic appearance is caused 

 by a film of fluid under the semi-transparent yellow skin of 

 the pupa, in numerous species of the family Nymphalidffi, 

 and that when the pupa is fresh, and the skin soft, the golden 

 bi-illiancy can be caused to shift its position by turning the 

 pupa about. 



Some years ago 1 reared a large brood of the larvae in an 



