SONG BIRDS UF ORCHARD AND WOODLAND. 205 
this species that I first became aware of the usefulness of birds 
toman. 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 larve 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 Vireo. It is most astonishing to 
see him pick up caterpillar after caterpillar from twigs and 
foliage, where with 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 
bis 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 ina 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. 
