BOARMID.E—BISTON. 121 



In tlie same collection is a black example, and one of a very- 

 pale brown, almost transparent. Scottish specimens, which 

 are rare, are not all uniformly pale grey ; a male from Perth- 

 shire in J\Ir. Percy Bright's collection, although of this ground 

 colour, has the black lines and band so much suffused and 

 intensified as to form a very handsome variety. A strong 

 tendency toward grey colouring without the yellow dusting 

 seems to exist in the Eastern Counties ; while in Oxfordshire 

 there is sometimes increased size, a specimen taken by Mrs. 

 Bazett in the beech woods near Reading being a quarter of 

 an inch larger in expanse of wing than usual. Finally, the 

 Rev. Joseph Greene possesses a beautiful male in which there 

 is considerable increase in the yellowish-white area, which ex- 

 tends into the middle of the wings and upon the costal margin ; 

 and another having six deep black transverse stripes. 

 On the wing in March and April. 



Larva stout, cylindrical, smooth ; sides slightly puckered ; 

 head rather bifid, flattened in front, smaller than the second 

 segment, greyish-purple, dusted with black ; mouth dark 

 brown, edged with yellow ; twelfth segment with two slight 

 dorsal eminences ; greyish-purple, clouded and mottled with 

 darker, the whole surface covered with fine threadlike longi- 

 tudinal black lines; front edge of second segment con- 

 spicuously yellow ; two yellow spots on the back and one 

 immediately following the spiracle, on the sixth, seventh, 

 eighth, and ninth segments ; dorsal eminences on the twelfth 

 tipped with dark grey; thirteenth dusted with black and 

 having two small projections behind ; legs pale pink tipped 

 with brown ; the undersurface between these light yellow ; 

 space between the prolegs pale browuish-ochreous. When 

 very young it is almost black, distinctly banded with yellow 

 at the incisions. (0. Fenn.) Sometimes the greyish-purple 

 ground colour is exchanged for pale yellowish-grey, or for 

 green-grey or red-brown. 



May to July, on lime, elm, poplar, willow, sallow, birch. 



