SONG BIRDS OF ORCHARD AND WOODLAND. 205 



this species that I first became aware of the usefulness of birds 

 to man. One sunny day in early boyhood I watched a Vireo 

 singing in a swampy thicket. He sang a few notes, his head 

 turning meanwhile from side to side, his eyes scanning closely 

 the near-by foliage. Suddenly the song ceased ; he leaned 

 forward, sprang to another twig, snatched a green caterpillar 

 from the under side of a leaf, swallowed it, and resumed the 

 song. Every important pause in his dissertation signalized 

 the capture of a larva. As the discourse was punctuated, a 

 worm was punctured. It seems as if the preaching were a 

 serious business with the bird ; but this seeming is deceptive, 

 for the song merely masks the constant vigilance and the 

 sleepless eye of this premium caterpillar hunter. In the 

 discovery of this kind of game the bird has few superiors. 

 He goes about it in the right way. Minot says : "They have 

 never struck me as very active insect hunters, since they 

 devote so much of their time to their music." This is true, 

 but the Vireo does not hunt active game so much as it seeks 

 those defenceless larvae that must depend upon their protec- 

 tive shape and coloring to conceal them from their enemies. 

 These devices may insure them against some of their insect 

 foes, but not against the Yireo. It is most astonishing to 

 see him pick up caterpillar after caterpillar from twigs and 

 foliage, where Avith the best glasses our untrained eyes can 

 discern " nothing but leaves." And so the bird sings the 

 livelong day, to while away the time as it searches over the 

 foliage. This habit of song becomes so strong that the male 

 bird sings while sitting on the nest to relieve his faithful 

 mate. He sings all summer, and even into the fall. When 

 his hunger is temporarily satisfied, he will sit on a twig and 

 sing for minutes at a time. His common notes are an alarmed 

 chatter and a querulous cry. 



The Red-eyed Vireo is now becoming well recognized as 

 a great insect eater. Mr. Arthur G. Gilbert informed me 

 that he fed a young bird of this species a hundred grass- 

 hoppers in a day. When the last grasshopper had been swal- 

 lowed the bird was well filled, for the tips of the insects' 

 wings projected from the bird's bill. This Vireo is one of the 

 most effective enemies of the gipsy moth and brown-tail moth. 



