RELATION OF VASTATOR TO OTHER APHIDES. 10 1 



year, and I know that many rare insects, as the Camber, 

 well beauty, the death's head moth, and the unicorn hawk 

 moth, have been taken this year more abundantly than 

 usual. 



(405.) Insects are kept in bounds by atmospheric causes, 

 birds, bats, reptiles, and very mariy species of insects which 

 prey upon others. Therefore, when one insect shows it- 

 self in too great abundance, we must look out for the par- 

 ticular destroyer destined by nature to keep it within its 

 accustomed limits. 



The human species has frequently been threatened with 

 total destruction by the locust, and yet man still lives, and 

 the locust has returned to its proper limits in the circle of 

 creation. 



The last two or three years the vastator has threatened 

 millions of men ; but, doubtless, at last the harmony of the 

 universe will be restored, the super-abundance of the in- 

 sects will be checked and controlled, and man will be saved 

 from its attacks. 



CHAPTER XVII. 



RELATION OF THE VASTATOR TO OTHER APHIDES AND TO 

 FUNGI. 



Analogy between the different aphides (406 409). Probable effect 

 of the predominance of one species (410). Destructive power of 

 aphis (411). Relation of fungi to aphides (412). 



(406.) THE numerous species of Aphis bear a strong 



