LOSSES CAUSED BY INSECTS: NATURE'S CONTROL METHODS 37 



his manner of life is such as to drive away birds which might be valuable 

 aids in his struggle against pests, the situation changes rapidly for the 

 worse. 



Those who look on the bright side are confident that in time Nature 

 will reestablish a balance, and this is probably true. But Nature works 

 in centuries, and man cannot wait so long for results. 



Under these conditions artificial measures as contrasted with natural 

 ones must be taken if crops are to be raised, food obtained, and if health 

 is to be preserved, and these artificial methods for the control of injurious 

 insects need to be known, and the nature of their action understood. 



