106 BlRD FRIENDS 



annual loss due to the sapsucker is a million and a 

 quarter dollars. 



Destroying beneficial insects. Some insects are 

 helpful to man, such as the parasitic and predacious 

 insects that prey upon injurious insects, the bees and 

 wasps that pollinate fruit flowers, and the honey- 

 bee, which produces honey. It is to be expected that 

 birds in their search for insects would feed on the 

 beneficial forms as well as those that are injurious to 

 man. To what extent these insects form a part of 

 birds' food and how this compares with the amount 

 of injurious insects eaten are questions to be investi- 

 gated in determining the economic status of birds. 

 The worst offenders in this line of destroying benefi- 

 cial insects are found in the family of flycatchers, 

 including the phcebe, kingbird, chebec, and wood 

 pewee. These insects are also eaten to some extent 

 'by the swallows and warblers. 



Dr. Judd found in his studies of the "Birds of a 

 Maryland Farm," after an examination of about 

 seven hundred stomachs representing one hundred 

 and sixty-three species, that beneficial insects 

 formed four per cent of their food while injurious 

 insects formed twenty-seven per cent. This would 

 probably hold true for birds as a class, that their 

 food contains seven times as many injurious as 

 beneficial insects. The small size of many parasitic 

 insects helps to explain why birds feed on these in- 

 sects to such a small extent. 



