ANIMALS THAT DESTROY INSECTS 183 



are full grown, are very valuable in destroying insects, 

 grubs, etc., when they are feeding their young. 1 



Examination of the stomachs of different birds (see 

 Figure 107) shows what birds are of the greatest value to 

 the farmer. 



QUESTIONS AND EXERCISES. 



1. How does the ichneumon fly help the farmer? 



2. What is the food of lady bugs? 



3. Tell how the dragon fly lives, and what food it eats. 



4. Of what value are toads? 



5. What do house wrens eat? 



6. W T hy should most birds be encouraged to make their 

 homes near us? 



'During the outbreak of Rocky Mountain locusts in Nebraska in 1874-1877, 

 Prof. Samuel Aughey saw a long-billed marsh wren carry thirty locusts to her 

 young in an hour. At this rate, for seven hours a day, a brood would consume 

 210 locusts per day, and the passerine birds of the eastern half of Nebraska, al- 

 lowing only twenty broods to the square mile, would destroy daily 162,771,000 

 of the pests. The average locust weighs about fifteen grains, and is capable each 

 day of consuming its own weight of standing forage crops, which at $10.00 per 

 ton would be worth $1,743.97. This case may serve as an illustration of the vast 

 good that is done every year by the destruction of insect pests fed to nestling birds. 

 And it should be remembered that the nesting season is also that time when the 

 destruction of injurious insects is most needed, that is, at the period of greatest 

 agricultural activity and before the parasitic insects can be depended on to reduce 

 the pests. The encouragement of birds to nest on the farm and the discouragement 

 of nest robbing are therefore more than mere matters of sentiment; they return 

 in actual cash equivalent, and have a definite bearing on the success or failure of 

 the crops. Year Book of the Department oj Agriculture. 



