330 LEPIDOPTERA. 



six parallel slender white lines extend the whole length of 

 the body ; spiracular line broader, white, placed on a narrow 

 raised ridge or wrinkling of the skin ; spiracles black ; usual 

 raised dots minute, white, having very small straight bristles ; 

 undersurface and prolegs paler green ; legs still paler and 

 tipped with yellow-green, rather large and strong ; anal and 

 third pair of prolegs also very robust, the other three pairs 

 smaller and decreasing in size to the first, also much less in 

 use, since the mode of walking is to form a complete loop 

 like a Geometra. Occasionally the green ground colour is 

 replaced by brown. Very active and lively, feeding eagerly 

 by day ; by no means disturbed even by examination and 

 description. 



April and May or the beginning of June on birch, feeding 

 when young in preference upon the catkins, later upon the 

 leaves. 



Pupa long, narrow, and very uniformly cylindrical, leg 

 and antenna-covers faintly raised above the generally smooth 

 surface and, with the wing-covers minutely sculptured in 

 very fine transverse incised lines, which render these portions 

 rather dull ; head a rounded projecting knob, eyes and 

 mouth-cover wrinkled ; dorsal surface also wrinkled, and 

 ridged at the segments ; abdominal segments edged on both 

 margins by strong sharp ridges, the incisions between deeply 

 incised and angulated ; the front ridges deeply pitted ; anal 

 segments smooth and thick, but rounded, and furnished with 

 a small rounded knob as a cremaster, with two short spikes 

 widely divergent and bent back ; whole surface moderately 

 shining, pitchy brown, bright in the smooth portions. In a 

 very neatly excavated chamber in the substance of soft bark, 

 the chamber being at right angles with the entrance hole, 

 across which is built a silken diaphragm. 



In this condition through the winter. 



The male moth flies in the sunshine with great activity at 

 thirty to fifty feet from the ground, sometimes higher, or 



