The Processionary : the Nest 



Expert spinners though they be, they seem 

 as unconscious of the ruin of their work as 

 the spools in a factory are of a broken thread. 

 They could easily make good the damage by 

 stopping up the breach with the silk that is 

 lavished elsewhere without urgent need; they 

 could weave upon it a material as thick and 

 solid as the rest of the walls. But no, they 

 placidly continue their habitual task; they spin 

 as they spun yesterday and as they will spin 

 to-morrow, strengthening the parts that are 

 already strong, thickening what is already 

 thick enough; and not one thinks of stopping 

 the disastrous gap. To let a piece into that 

 hole would mean weaving the tent all over 

 again from the beginning; and no insect, how- 

 ever industrious, goes back to what It has 

 already done. 



I have often called attention to this feature 

 in animal psychology; notably I have de- 

 scribed the ineptitude of the caterpillar of the 

 Great Peacock Moth.^ When the experi- 

 menter lops the top off the complicated eel- 

 trap which forms the pointed end of the co- 

 coon, this caterpillar spends the silk remaining 



^In the course of an essay on aberration of instinct in 

 a certain Mason-wasp which is not yet translated into 

 English. — Translator's Note. 



41 



