﻿14 BULLETIN 1355, U. S. DEPAETMENT OF AGEICULTUKE 



A^fIMAL 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 vu-eo, 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. 



Hemiptera. — 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 hymenopterans 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 



