FOOD HABITS OF THE VIBEOS 
11 
weevils, which form almost a fourth (24.82 per cent) of the totaL 
The beneficial beetles eaten are almost all of the family Coccinellidae, 
or ladybirds, well-known as enemies of plant lice and scale insects. 
Thirteen species of ladybirds have been identified from stomachs of 
the Philadelphia vireo, and these make up a little more than a fifth 
of all the beetles consumed, or about 5 per cent of the total food. 
This large percentage, however, is more than offset by the remaining 
beetles most of which are species of distinctly injurious tendencies. 
The leaf-eating beetles ( Chrysomelidae) lead the list of families of 
injurious beetles, with a total of 7.99 per cent. During May the leaf 
eaters seem to be more abundant, as then they make up a total of 
nearly 11 per cent. This high percentage is not maintained through- 
out the year, however, and by September only 4.59 per cent of the 
food is of this description. Next in order of importance from the 
viewpoint of quantity consumed come the leaf chafers and dung 
beetles (Scarabaeidae) . The true dung beetles should be considered 
Fig. 3.— Yearly summary of the various items in the food of the Philadelphia vireo (Vireosylva philadel- 
phica), based on the analysis of the contents of 75 stomachs 
mildly beneficial, inasmuch as they carry beneath the surface 
quantities of fertilizing elements. As the very nature and mode 
of life of the vireo, however, prevents it from catching many of these, 
they have been included with their injurious cousins, the leaf chafers. 
Taken together, they represent a total of 6.94 per cent, all eaten 
before September. In June the percentage is very high (14.08), 
and it is almost all leaf chafers. 
A third group of injurious beetles found with some frequency in 
the stomachs is the suborder Rhynchophora, or weevils, which make 
up 3.43 per cent of the food of the Philadelphia vireo. Although 
this proportion is not very great, it appears to be evenly distributed 
throughout the year. The wood-boring beetles, Buprestidae and 
Cerambycidae, and the plant-feeding Elateridae together make up a 
little less than 1 per cent of the total. Except in June, when these 
forms exceed 2 per cent, the item is insignificant. The rest of the 
beetles eaten, including beneficial, injurious, and neutral forms in 
