ELEMENTS OF AGRICULTURE 



CHAPTER XLIL— Insectivorous Birds 



212. Damage Done by Insects. — Before taking up 

 insectivorous birds, let us try to get some idea of the 

 damage done to farm crops each year by insects. 



Harmful insects feed mainly on the young and tender 

 foliage of growing plants, but they also attack the seed, 

 fruit, stem, and roots. In fact every portion of the 

 plant is used as food by various insects, and no plant is 

 eafe from their attacks. Of course, not all insects are 

 harmful. There are insects that prey on injurious 

 insects, but, unfortunately, the harmful insects far out- 

 number the beneficial kinds. Birds prey largely on the 

 injurious kinds. 



A careful estimate places the average damage done 

 annually by insects in the State of Illinois at twenty 

 millions of dollars, which means that the damage 

 averages 5(3 cents to each acre.* Fifty-six cents per 

 acre for the damage done by insects is hardly an over- 

 estimate, and it is probable that there are few farmers 

 whose crops are not damaged to this extent. But let 

 us take for our example the State of Virginia and con- 

 sider only the cultivated land. Forests we will not 

 consider, though they are often much damaged by insect 

 pests. We will assume that there are 9,000,000 acres 

 of land under cultivation in Virginia, and that the 

 crops from this amount of land arc damaged by insects 



♦Report of Conn. Board of Agr., 1899. p. 78. 



