189G.] ESSAYS. 79 



hundred and fifty million dollars to four hundred million dollars an- 

 nually. Professor James Fletcher, entomologist to the Canadian 

 government, places it at three hundred and eighty million dollars. 



In considering the means to be used in combating injurious insects, it 

 first becomes us to inquire what means are used by nature to regulate the 

 increase of our insect enemies and to hold them in check. Although 

 meteorological and climatic conditions play a considerable part in the 

 regulation of insect increase, the principal means provided by nature 

 for this purpose are (1) the various forms of animal life which prey 

 upon insects ; (2) certain bacterial or fungoid diseases. While little 

 can be done by the farmer to foster and direct the increase of useful 

 insects which prey upon other insects, while he is unable to direct or 

 control the diseases which serve to hold injurious insects in check, he 

 can do much toward fostering and protecting the vertebrate animals 

 which prey upon insects, especially the birds. Birds appear to be 

 especially designed to hold our insect foes in check. Their peculiar 

 structure, their powers of vision and flight render them particularly 

 adapted to this work. Their appetites and digestive powers are sec- 

 ond only to those of insects. Audubon says a woodcock will eat its 

 own weight of insects in a single night. Professor Treadwell shows 

 that it was found necessary to feed a young robin forty-one per cent, 

 more than its own weight in worms in twelve hours to insure its 

 healthy growth and development; that it would consume nearly half 

 its own weight of beef in a day. A man at this rate would eat about 

 seventy pounds of flesh daily. Professor Wood estimates that a man 

 would have to consume in each twenty-four hours, sixty-seven feet of 

 a sausage nine inches in circumference, in order to eat as much in pro- 

 portion to its bulk as the redbreast whose daily food is considered as 

 equivalent to an earth-worm fourteen feet long. 



Ornithological and entomological publications relate many instances 

 of the usefulness of birds. Instances are given where trees and crops 

 have been saved from destruction by the timely arrival of flocks of 

 certain species of birds who have destroyed the insects. During the 

 locust, invasions in the west many fields of grain, vegetable gardens 

 and other crops were saved by birds which destroyed the " hoppers" 

 before they had attained sufficient growth to do much injury. When 

 the Mormons first settled in Utah their crops were saved from the 

 devastations of the mountain crickets by the timely arrival of flocks 

 of gulls who destroyed the crickets. 



Many of the worst enemies of agriculture are held in check by birds, 

 and wherever these birds are destroyed the insects increase. Birds 



