TRlFfD.^. 367 



slender blackish transverse stripe, and before the apex a 

 blackish costal triangle. Hind wings shining yellowish- 

 white ; costal margin broadly dusted with bluish and ashy- 

 grey ; central crescent, and a transverse stripe beyond it, 

 blackish ; and a black line at the hind margin. Body silvery- 

 grey ; legs brown, barred with white ; leg tufts greyish-white. 



Extremely constant in colour and markings; but I have 

 seen a specimen from the North of Ireland in which the 

 subcostal, median, and subdorsal nervures of the fore wings 

 are darkly coloured, so that three very straight, nearly 

 parallel lines extend almost the whole length of the wings. 

 Mr. F. N. Pierce has an exquisitely lovely vai'iety taken near 

 Liverpool, pale green throughout, with but faint traces of 

 the usual markings. 



On the wing in August and the beginning of September. 



Larva plump, cylindrical, but with the segmental divisions 

 rather well marked ; head a little smaller, pale brown, with 

 a V-shaped mark in the front of the face ; body variable in 

 colour, the ground colour being usually some shade of slate- 

 grey, dark or pale ; dorsal line usually very pale grey or 

 white, swelling out on the back of each segment of the body 

 so as to form a chain of spindle-shaped markings joined at 

 their ends, and edged on each side by a slender, undulating 

 brown or blackish line ; adjoining this is the subdorsal stripe, 

 broad, red-brown, light red, or dull brown, edged below with 

 a fine blackish line and a slender yellowish or whitish stripe, 

 which again is followed by a broad lateral stripe of blue- 

 grey, or slate-grey, or even pale lilac-grey, at the lower 

 margin of which are the black spiracles. Sometimes this 

 lateral stripe is dusted with darker atoms. Legs and under- 

 surface very pale grey, the sub-spiracular stripe sometimes 

 of that colour, in other cases yellowish. Sometimes the 

 dorsal line is bluish-grey and all the stripes of full colouring ; 

 in other cases, and especially when quite full fed, all the 

 colouring is paler. Usually the second segment is paler 



