DESTROYERS OF INSECT PESTS 81 



out the whole country, that a brief summary may be 

 given. During this period 163 species of birds were 

 observed. The stomachs of 298 birds were collected 

 and examined. Considering the food of all the birds 

 collectively, exclusive of the English sparrow, it was 

 found that beneficial insects formed 4 per cent of the 

 food, while injurious insects formed 27 per cent; grain 

 formed li per cent, while weed seeds formed 18 per 

 cent. This food may be grouped as follows : — 



Food beneficial to man Food injurious to man 



Per cent Per cent 



Beneficial insects .. . 4 Injurious insects. .. . 27 



Grain \\ Weed seeds 18 



Total 5\ Total 45 



The injurious food is thus seen to equal in amount 

 nine times the beneficial food; or, in other words, the 

 birds did nine times as much good as harm. A 

 small amount of cultivated fruit was eaten, but the 

 exact per cent was not given in the bulletin. 



Birds and human health. It is now well known 

 that some insects carry diseases and thus are the in- 

 direct causes of sickness and death. The house-fly 

 and mosquito are the two most common and deadly 

 insects in this way. The house-fly carries typhoid 

 fever, tuberculosis, children's diseases of the alimen- 

 tary canal, and many other diseases. Mosquitoes 

 carry malaria and yellow fever, and are the only 

 means known by which these diseases are carried 

 from one person to another. And even in the north- 



