114 THEORY OF THE DISEASE. 



(452.) The impairment of the health of the whole plant 

 might lead us to suppose that it would cause the destruc- 

 tion of the creature. Not so, however ; Nature has 

 wonderfully ordained that the exhaustion of the plant 

 should have an influence upon the animal. When the 

 plant no longer retains sufficient vigor to supply nourish- 

 ment to the insect, the creature ceases to reproduce, it 

 takes the pupa form, and finally emerges from that transi- 

 tory condition in its final or more glorious state, when 

 countless millions, in the form of a cloud, take flight, soar 

 aloft, and traverse mountains, valleys, streams, lakes, seas, 

 and even kingdoms, destroying in their progress some of 

 the most useful foods of man.* 



(453.) Such beautiful illustration of the perfection of 

 nature almost compels the naturalist for a time to forget 

 the great calamity which has happened to the human race 

 by this little insect. This minute creature, which by 

 itself may appear to be scarce worth our notice, when 

 congregated in masses, becomes an army, terrible and 

 invincible even to the English nation. Napoleon, with all 

 his army, with all his bravery, never dared set foot on the 

 English shore : this little insect has baffled science, poli- 

 tics, and power ; it has invaded our territories, it has, in 

 spite of all our armies, fleets, and forts, come into our 

 lands, and taken from our possessions the food destined to 

 nourish our children. 



* This destroying cloud, wafted about with the winds, settles 

 here and there upon some ill-fated locality : hence the prevalence 

 of a wind in one direction may influence to a great extent the more 

 or less extensive damage in various aspects. 



