﻿16 



BULLETIN 1355, U. S. DEPAETMENT OP AGRICULTUEE 



examination of which is the very small percentage of vegetable 

 matter — only 1.74 per cent of the total. (See fig. 5.) 



ANIMAL FOOD 



The animal food of the yellow- throated vireo makes up 98.26 per 

 cent of the total, and may be divided as follows: 95.82 per cent 

 insects, 2.38 per cent spiders, and 0.06 per cent other animal matter. 



Lepidoptera. — More than 42 per cent of the yearly food of the 

 yellow-throat is made up of butterflies and moths in their different 

 stages. As in the food of other species of this family of birds, cater- 

 pillars are the most important item (23.1 per cent). Almost all 

 adult insects of this order found in the stomachs were moths, and 

 together made up a total of 19.35 per cent. There appears to be no 

 definite time of year when the birds prefer lepidopterous food, 

 although in September a maximum of 36 per cent was reached for 



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■is^/^>it^ 





Fig. 5.— Monthly proportions of the various items in the food of the yellow-throated vireo (Lanivireo 

 flavifrons), based on the analysis of the contents of 160 stomachs, with the average of each item for the 

 year 



caterpillars, and the same month showed an advance of 7 per cent 

 over the previous month's total of 43.73 for all lepidopterans. 

 Adults were consumed in greatest quantity in June, more than one- 

 third (35.15 per cent) of ail the food taken that month being of this 

 character. 



Hemiptera. — In quantity consumed, the bugs occupy second place 

 in the list of food items of the yellow- thro at. Two-thirds of those 

 identified are referable to the family of stink-l^ugs (Pentatomidae) , 

 15.5 per cent for the year. The remaining, 7.62 per cent, is composed 

 of such forms as assassin bugs (Reduviidae) , scale insects (Coccidae), 

 and leaf hoppers (Membracidae) . Owing to the great discrepancy 



