356 BULLETIN 19 7, UNITED STATES NATIONAL MUSEUM 



Food. — Of the 84 stomachs of the Philadelphia vireo in the collec- 

 tion of the Biological Survey, Dr. Edward A. Chapin (1925) found 

 that only 75, taken in May, June, and September, contained enough 

 food to show the percentages. 



All but 4.34 percent of the animal food consisted of insects, the 

 remainder being spiders. Lepidoptera formed the largest item, 24.13 

 percent of which were caterpillars and 2.17 percent adult moths and 

 butterflies ; in September the percentage of these lepidopterous items 

 rose to 45.53, or nearly half of the entire food for the month. 



Coleoptera ranked next, 24.82 percent for the year. "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 percent of the total food." Tliis is a bad show- 

 ing for this vireo, but it is more than offset by all the injurious 

 beetles destroyed, such as leaf -eating beetles (Chrysomelidae), 7.99 

 percent; weevils (Rhynchophora), 3.43 percent; wood-boring beetles 

 (Buprestidae and Cerambycidae) and the plant-feeding Elateridae, 

 together, less than 1 percent. The mildly beneficial dung beetles and 

 the leaf -chafers (Scarabaeidae) taken together amount to 6.94 percent. 



Of the Hymenoptera, "approximately 14 percent of the annual sub- 

 sistence of the Philadelphia vireo is composed of wasps, bees, and 

 related insects. Here are to be found some of the most beneficial of 

 all insects, the parasitic ichneumon flies and the minute chalcids. On 

 the other hand, the kinds of ants eaten are usually injurious, espe- 

 cially the large, black, carpenter ants {Camponotus herculeanus) , and 

 even if some of them do no direct damage they are indirectly injurious 

 in fostering plant lice." 



Flies (Diptera) form 11.76 percent of the food, including midges 

 and both injurious and beneficial forms. True bugs (Hemiptera) 

 make up 10.46 percent of the annual food, including the injurious 

 stink bugs but not the useful stink bugs or the beneficial assassin bugs, 

 so that the score is good in this group. Other insects amount to 

 only 1.14 percent. 



The seasonal average of vegetable food was but 7.22 percent of the 

 whole, although in September it amounted to 18.71 percent. The 

 fruits identified were bayberries, wild rose hips, and wild grapes, 

 but no cultivated fruits or seeds w^ere found. 



Dr. Lewis (1921) says of the feeding habits of this vireo : 



The birds fed usually in the border of the woods, among the lower limbs of 

 the Red Oalcs and Red Maples, less often among the White Birches or the Rock 

 Maples. The pair which resided among the White Birches a hundred yards 

 behind my house probably fed among them. 



