18 
BULLETIN 1355, U. S. DEPARTMENT OF AGRICULTURE 
SUMMARY 
There can be no reasonable doubt that with an annual consumption 
of 42.25 per cent of caterpillars and moths, the yellow-throated 
vireo is to be classed as a beneficial bird. Adding to this the 7.62 
per cent representing bugs, most of which are injurious, and the 10.46 
per cent of distinctly injurious beetles, the total of 60.53 per cent 
is a fair estimate of injurious insects in the bird's food. To offset 
this, only 0.62 per cent is made up of the benficial ladybird beetles. 
The rest of the food is neutral economically and may be passed with 
this mention. This is a record to commend the yellow-throated 
vireo, and one that is not closely approached by other birds of this 
family. 
THE BLUE-HEADED VIREOS 
Lanivireo solitarius, subspp. 
The blue-headed vireos, or, as they are sometimes called, the 
solitary vireos, are of fair abundance over a wide range, including all 
of the United States, most of Canada, and parts of Mexico and Lower 
California. The material used in this study includes 306 well-filled 
stomachs, collected in all months except December. January and 
November are represented by but 8 and 9 stomachs, respectively, 
whereas the greatest number for any one month, 79, is for May. 
Twenty-three other stomachs, only partially filled, gave some addi- 
tional data regarding food items. 
The blue-heads eat about twice as much vegetable food as the 
yellow- throat (3.68 per cent), but otherwise the diet is similar in its 
constituent items. (See fig. 6.) 
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Fig. 6.— Monthly proportions of the various items in the food of the blue-headed vireos (Lanivireo solitarius , 
subspp.) , based on the analysis of the contents of 306 stomachs, with the average of each item for the year 
