DESTROYERS OF INSECT PESTS 75 



also, is based on the reports of the Bureau of Bio- 

 logical Survey : — ■ 



Injurious insect Number of species of 



birds feeding on it 



Plum curculio 7 



Grain aphids 9 



Potato-beetle 26 



Codling moth 36 



Birch plant-lice 38 



Brown-tail moth 39 



Alfalfa weevil 45 



Gypsy moth 46 



Scale insects 57 



Boll weevil 66 



Below are given some estimates that have been 

 made of the number of insects destroyed by birds : — 



Professor E. D. Sanderson estimates that the 

 chickadees in the State of Michigan destroy annu- 

 ally about 8,000,000,000 insects. 



In the States of Virginia and North Carolina it is 

 estimated that the bob-white alone eats 340 tons of 

 insects from June 1 to August 1. 



Mr. Chester A. Reed estimated that in the State 

 of Massachusetts the birds devour 21,000 bushels 

 of insects each day during the summer season. 



Mr. Bruner gives the following estimate of the 

 number of insects destroyed in the State of Ne- 

 braska: — 



Allowing 25 insects per day as an average diet for each 

 individual bird, and estimating that we have about one 

 and one half birds to the acre, or in round numbers 

 75,000,000 birds in Nebraska, there would be required 

 1,875,000,000 insects for each day's rations. Again, es- 



