114 LEPIDOPTERA. 



and usually elevated. Head greenish-grey or yellowish-grey ; 

 body whitish-grey, more or less tinged with pink or brown or 

 yellowish ; the two hinder segments more yellow-brown or 

 pinkish ; dorsal line broadly orange, edged with brown 

 on some of the segments, but on others almost obliterated, 

 well marked on the front of the dorsal humps ; subdorsal 

 line a mere darker shade of the ground colour ; spiracular 

 line similar but more distinct, broader, and edged below with 

 yellow or white ; spiracles ringed with black ; undersurface 

 and legs darker grey. Sometimes the raised hinder segments 

 are richly clouded with orange, and have white lines on the 

 upper portion of the hump. 



June and July, and usually, in the southern districts, a 

 second generation in August and September. On sallow 

 and willow ; more rarely on poplar and aspen ; feeding on the 

 leaves, clinging much to the twigs or leaf-stalks, holding on 

 with considerable force, and from its singular form, which, 

 with head and tail raised, and conspicuous humps, is quite a 

 zigzag (hence its name), may easily be passed over as a dead 

 and twisted leaf or catkin. When feeding on poplar it is 

 sometimes of a bright pea-green. It is hardy and easily reared. 



Pupa round, cylindrical, rather stumpy ; red-brown ; glossy 

 on the abdomen and tail, dull on the wing-cases. Subter- 

 ranean, in a cocoon of silk and earth, sometimes at the root 

 of a tree, doubtless more frequently under a bush. In this 

 condition through the winter. 



The moth flies only at night, and comes readily to a light 

 placed in its haunts, though not often to gas-lamps in the 

 suburbs of towns. In fens and marshy places it is taken 

 freely by this method. Otherwise it is rarely taken upon the 

 wing, or indeed in any manner in the moth state, nearly all 

 the specimens in collections being reared. Probably it sits in 

 the daytime upon branches of trees rather than their trunks, 

 and in the thick parts of bushes, where it is not easily seen. 



Apparently found throughout the United Kingdom, wher- 



