266 



THE INSECT WOULD. 



This packet is more or less large according as the height ascended 

 by the caterpillar is greater or less. All the turns of the thread 

 which compose it are entangled. So the caterpillar does not con- 

 sider it of any value ; as soon as it can walk, it gets rid of it, sets 

 its legs free, and leaves it behind before it has taken one or at 

 most two steps. Each time, then, costs it the cord it made use 

 of to effect its ascent, but this is an expense it can always be at 

 whenever it likes ; it has in itself the source of the matter necessary 



for the composition of the thread, 

 and it is a source in which that 

 which was drawn off is being con- 

 tinually re-supplied. Moreover, 

 spinning the thread costs the 

 caterpillars little; indeed, the 

 loopers economise this thread so 

 little that most of them leave it 

 behind them wherever they go." 

 They are found on many trees, 

 but particularly on the oak, whose 

 foliage they often entirely devour. 

 They burrow into the ground to change into chrysalides, and 

 undergo all their metamorphoses in the course of the year. Others 

 do not become perfect insects till the autumn, or sometimes not even 

 till the following spring. A few assume the perfect state in winter. 

 There are, indeed, some of these, such as the males of the Hyber- 

 niaSj which fly about on the foggy evenings of November. The 

 females of this genus have either no wings at all, or else only 

 rudimentary ones. Two species, the Hybernia defoliaria, or Winter 



Fig. 262. Hybernia leucophearia, male. 



Fij?. 263. Winter Moth (Hybtrnia 

 df/oliaria), male. 



. 264. Winter Moth (Hybernia 

 defoliaria), female. 



moth, and the Cheimatobia brumata, abundant here, are very 

 common in the environs of Paris. 



