106 NESTS AND OTHER STRUCTURES 



provides for the occasion a winter residence, which 

 is occupied only during the cold season. For this 

 purpose it eats the sides of a willow-leaf nearly to 

 the midrib, for about one third the distance from 

 the tip, ordinarily selecting for the purpose a leaf 

 near the end of a twig ; the opposite edges of the 

 rest of this leaf it brings together, and not only 

 fastens them firmly with silk but covers this nest 

 outside and inside with a carpet of light-brown 

 glossy silk, so that the leaf is nearly hidden ; nor 

 is this all : it travels back and forth on the leaf- 

 stalk and around the twig, si3inning its silk as it 

 goes, until the leaf is firmly attached to the stalk, 

 and in spite of frost and wind will easily hang 

 until spring. Following the projecting midrib, 

 the caterpillar creeps into this dark cell, head fore- 

 most, and closes the opening with its hinder seg- 

 ments, all abristle with spines and warts. The 

 other species of the same genus, the red-spotted 

 and the banded purple, have the same habits ; the 

 latter feeds on birches, and if we examine these 

 trees in early spring, when all sorts of ichneumon 

 flies are just beginning to wander about in search 

 of prey, we can hardly fail to be struck by the de- 

 ceptive resemblance these hibernacula of the banded 

 purple bear to the opening buds and curving ter- 



