274 BOARD OF AGRICULTUEE. [Pub. Doc. 



Then from the very fact of their great numbers there is an 

 abundance of food offered their natural enemies, and the 

 latter increase to such an extent as to destroy the greater 

 part of the army worms, whereupon the insect apparently 

 disap})ears. This shifting relation between the host insect 

 and its natural enemies is best expressed by the term so 

 frequently used by biologists, "the balance of nature," and 

 this "balance" is the factor which controls all insect out- 

 breaks. It would seem probable that the localities suffering 

 most from the army worm this year will be exempt next 

 season, although it is possible that a sufficient number of the 

 insects may have survived in some places to cause some de- 

 gree of damage. In the parts of the State where but little 

 damage has resulted from the army worm this year there is a 

 greater chance that the pest will be abundant next season, 

 and here particular attention should be given to the burning 

 over of fields. When the present outbreak subsides there 

 probably will not be another one for several years. 



