366 LEPIDOPTERA. 



straight ; silky-white with a very faint tinge of brown dusting 

 along the dorsal and hind marginal regions; on the costal 

 margin are two conspicuous triangular black or reddish-black 

 spots, from each of which arises a slender transverse line of 

 faint cloudy- brown dots ; near the first of these is a small 

 black discal dot ; cilia white, with a faint brown line along 

 the base. Hind wings broad, rounded, but with the anal 

 angle squared, white ; central spot minute, black ; midway 

 between it and the hind margin is a slender, curved and 

 dotted, pale brown line ; cilia white. Female accurately 

 similar. 



Underside white, the fore wings shaded towards the costa 

 with smoky-brown ; each wing has an elongated, central, 

 black cloudy dot. and beyond it a faint transverse brownish 

 line. Body white ; legs whitish-brown. 



Not very variable ; but the size of the two costal spots is 

 somewhat uncertain and also their position — nearer or farther 

 apart — and the dotted transverse lines arising from them are 

 similarly shifted. These lines also are often nearly obsolete ; 

 but more rarely are rather distinct, with also traces of central 

 and subterminal lines ; this last form being apparently most 

 frequent in the New Forest. Occasional specimens have a 

 smoky tinge over the cilia. An example in Mr. Sydney 

 Webb's collection has suffused streaks running in brown lines 

 the whole length of the fore wings ; another is devoid of the 

 inner black costal spot; and one of the late Mr. F. Bond's 

 specimens is pure white, absolutely spotless. 



On the wing in May and June. 



Larva rather stout, smooth, cylindrical ; head yellowish- 

 green, dusted with purple ; body dark velvety green ; dorsal 

 surface with a row of irregularly diamond-shaped purple 

 spots ; spiracular line very minute, threadlike, yellow ; in- 

 cisions of the segments yellow ; spiracles black ; undersurface 

 whitish-green. (C. Fenn.) 



June and July, on wild cherry, and occasionally plum and 



