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FARM AND SCHOOL PROBLEMS. 



The Ichneumon Fly. 

 The Plant-louse Parasite. 



The Chalcid Flies. 

 The Proctotrypid Flies. 



THE TWO-WINGED PARASITES. 

 Tachina Flies. 



Insects and Their Insect Enemies. 



PROBLEMS. 



1. If the cotton crop in the U. S. amounts to 15,000,000 bales and 

 the loss of cotton caused by the Boll Weevil amounts to 400,000 bales 

 annually, what per cent of the crop is lost? 



2. If a bale of cotton weighs 500 pounds gross weight, and cotton 

 is worth 12c per pound, what is the value of the annual crop and what 

 is the annual loss on account of the boll weevil? 



