ACIDALIA INCANATA. 109 
near Bath. They fed on Polygonum aviculare until 
hybernation, which in their case extended over 
an unusually long period, as, in the spring fol- 
lowing, they did not recommence feeding until 
long after other hybernating species I had had 
begun to do so, although kept under precisely the 
same conditions. ‘his, however, cannot be taken as 
the natural habit of the species, whatever may have 
been the cause in this case, as my larve were conse- 
quently not full-grown until quite the end of June, or 
several weeks after the imagos ought to have been on 
the wing at large. 
Length nearly an inch and a half; the head has the 
lobes rounded, and is of equal width with the second 
segment; body slender, cylindrical, and of almost uni- 
form width throughout, tapering very slightly indeed 
toward the head; segmental divisions tolerably well 
defined, but do not overlap each other in the marked 
way which characterises so many of the species in 
the genus ; skin distinctly but very evenly transversely 
ribbed. 
Ground colour of the dorsal surface and head a very 
pale slaty-olive ; a dull olive stripe extends throughout 
the centre of the dorsal area, and encloses within it a 
very fine interrupted pale medio-dorsal line ; this 
olive stripe, however, is much darker on the last three 
segments than on any of the others; there is a pale 
yellowish, not very well defined, line along the sub- 
dorsal area, but there are no perceptible spiracular 
lines ; spiracles distinct, black. Ventral surface uni- 
formly of a pretty, very pale slaty-blue colour. 
The pupa is nearly half an inch long, smooth 
and polished, tolerably cylindrical, but attenuated 
towards the anal point; compared with the larva it 
is very stout. General colour of the dorsal surface 
pale brown; head and segmental divisions chocolate- 
brown ; wing-cases yellowish-green ; the anal tip 
brown. 
The imagos began to emerge July 23rd. (George 
