16 
BULLETIN 1355, U. S. DEPARTMENT OF AGRICULTURE 
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 
JIBIS BSSSBfSj 
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 all 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 t]ie yellow-throat. Two-thirds of those 
identified are referable to the family of stink-bugs (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 
