TRIFID^E. 183 



a slender white oblique streak. Hind wings rounded, dusky 

 white, much dusted and clouded with pale smoky-brown, 

 especially on the dorsal region and along the hind margin ; 

 cilia white, intersected by a brown line. Female similar, with 

 the body a very little stouter. 



Underside of the fore wings smoky-brown with a white 

 dash in the discal cell ; cilia dusky white. Hind wings white, 

 dusted with large brown scales, and with a faintly brown 

 hind-marginal band ; cilia white, dusted with brown. Body 

 and legs pale brown, dusted with white. 



Hardly variable except that the ground-colour of specimens 

 from Ireland seems to be of a yellower-brown tinge. 



On the wing in June. 



Larva with four pairs of prologs, the pair upon the eighth 

 segment small and undeveloped ; strikingly slender, especially 

 so as it attains its full growth of one inch ; head round, light 

 green with the upper lip whitish and the mouth black ; body 

 yellow-green with yellow segmental folds ; dorsal line dark 

 green though faint; subdorsal stripe primrose-yellow; spiracles 

 flesh-coloured and rather round, placed upon a deep yellow, 

 thread-like trachaea which shows faintly through the skin. 



When just hatched the young larva is of a pale yellowish- 

 green with very fine black dots and hairs, and at this time 

 the second pair of prolegs is ill developed and the first absent ; 

 at the end of a week the skin has become less clear and the 

 colour uniform light yellowish-green, with black raised dots. 

 In another fortnight it becomes longer and in proportion 

 more slender, of a more opaque velvety-green with the lines 

 beginning to show themselves. From this the adult colouring 

 is soon assumed. (Adapted from Buckler.) 



End of June to the beginning of August, on grasses — 

 Poa annua, P. aauatica, P. pratcnsis and other species, 

 especially those growing in marshy places. When at rest 

 lying stretched along the stem of the grass. When very 

 young it eats only the lower surface and parenchyma of the 



