14 BULLETIN 1355, U. S. DEPARTMENT OF AGRICULTURE 
ANIMAL FOOD 
Coleoptera. — Beetles make an annual total of 15.53 per cent, or 
nearly a sixth, of the food. Of these the ladybird beetles (Cocci- 
nellidae) are the most common. More than half of the coleopterans 
eaten are of this family, and more than one-twelfth of the food by 
bulk is composed of these valuable insects. During July about 26 
per cent of all the animal food is ladybirds, a remarkable percentage, 
for coccinellids are far from being a fourth as plentiful as all other 
insects together. The remaining 6.79 per cent of beetles is composed 
almost entirely of injurious forms, as leaf eaters, wood-boring forms, 
and weevils. 
Lepidoptera. — Caterpillars, usually injurious, make up the com- 
mendable percentage of 35.4 — more than a third of the yearly food. 
This is undoubtedly the most important item in the dietary of the 
warbling vireo, especially in spring, when it amounts to 69.74 per 
cent. The percentage of this item fluctuates more or less during 
the season, reaching its lowest ebb, 22.75 per cent, in September. 
The other forms of butterflies and moths, amounting to 4.99 per 
cent, are included with the caterpillars and make a grand total for 
this type of food of 40.39 per cent. 
Hernivtera. — The third class of animal food of the warbling vireo 
of sufficient importance to be considered separately is composed of 
the true bugs. These annually form 16.71 per cent of all the food, 
a little greater in quantity than the beetles. About a third of the 
bugs taken belong to the family of stink-bugs (Pentatomidae) . These 
are mostly large, ill-smelling insects and are considered by some as 
protected from birds by their odor. In the present case, however, 
the odor is either pleasing to the birds or at least not repelling. 
Other animal food. — The remainder of the food of animal origin 
amounts to a little more than a fifth of the total yearly food. The 
largest single item is made up of the different forms of flies (Diptera). 
During May, this item represents 22.63 per cent, or nearly a quarter 
of the food. From June on, however, there is a rapid decrease in 
the number eaten, so that by September, flies in the food constitute 
only 2.64 per cent. Considered for the whole year, a percentage of 
9.46 is reached, a fair index to the value of these insects in the food 
of the warbling vireo. To this is to be added 5.97 per cent, repre- 
senting the wasps, bees, and other hymenopterous insects consumed 
during the year. The incidence of hvmenopterans is paralleled by 
that of dipterans, May being the month of greatest consumption, 
here equaling 12.02 per cent. 
All other insects eaten together form the comparatively small 
percentage of 4.44. Only during August, when grasshoppers are 
abundant and a convenient form of food, does this item assume 
importance, at which time it forms 12.29 per cent of the monthly 
sustenance. 
With the exception of a few snails, a mere trace, the rest of the 
animal food is composed of spiders, an almost insignificant item for 
the year, but amounting in June to 3.03 per cent. 
VEGETABLE FOOD 
The vegetable food of the warbling vireo is made up in great part 
of the smaller wild fruits, as cherry, sassafras, bayberries, and black- 
berries. During the early part of the year vegetable matter appears 
