210 THE UNIVERSE. 



of a simple butterfly ; but its caterpillars sometimes multi- 

 ply to such an extent that it is necessary to exterminate 

 them utterly in order to preserve the forest from ruin. In 

 one part the woodmen and their families, who are called 

 out en masse, are occupied in crushing these destructive 

 creatures upon the trees. In another the others are cutting 

 off the infected districts by ditches, in order to check the in- 

 vasion of the caterpillars, which, when they have devoured 

 everything in one place, proceed in immense bands to in- 

 vade the healthy localities. 



But in spite of so much labor, man is sometimes van- 

 quished by the insect, and there only remains one last re- 

 source, that of setting fire to the forest and burning the 

 invaders. 



All this war of extermination, of which we have just 

 given a succinct account, is directed against only a small 

 number of our enemies, as for the most part they are able 

 to keep out of the power of the cultivator, and their formi- 

 dable army defies our weakness. 



These extensive operations are undertaken especially 

 against certain night-moths, for it is among the simple 

 moths that we find insects which are to be classed among 

 the most destructive ravagers of the forests. They are at- 

 tacked in their three different phases. Their caterpillars 

 are crushed as they climb the trees. When, after devouring 

 a complete section of the wood, they pour forth in serried 

 columns to attack a sound part, they fall into trenches hol- 

 lowed out by the pioneers; and when they fill these, they 

 are stifled in a heap by covering them over with earth. 

 The great fires lighted at night are directed against the 



