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break open the webs of the tent caterpillars. Most of the birds that feed 
upon it attack the young larve when they are out of the web. A few 
species, Such as orioles, vireos, and cuckoos, tear open the webs, and 
in some cases destroy every caterpillar contained within. Some species 
tear open the webs, carrying parts of them away to be used as material 
for nesting, thus opening the way for other birds to attack and destroy 
the caterpillars in their nests. 
The most striking instance which has come under our observation of 
the regulating influence exerted by birds on the increase of hairy cater- 
pillars occurred in July, 1899, at Georgetown, Mass. Here a swarm of 
gipsy caterpillars had increased unnoticed, defoliating the trees, both 
deciduous and coniferous, and all the shrubs over a space of, perhaps, 
2 acres. When the outbreak was discovered in July the caterpillars 
were nearly full grown and some were pupating. It was remarked at 
once that there were not enough larve to account for the injury which 
had been done. Many dead and dying larve and pupez were found 
scattered about on the ground under the trees. These were examined 
and found to have been injured, apparently, by the beaks of birds. 
Small flocks of crows were constantly feeding in the grove, except when 
driven out by visitors, and would return immediately when the coast 
was clear. Vireos, chickadees, and other birds were observed feeding 
on the caterpillars. Mr. Mosher was detailed to watch the locality for 
afew days. He found that the crows, jays, tanagers, chickadees, and 
other birds which abounded in the vicinity were destroying thousands 
of the larve, pup, and imagoes. As there were very few effective 
parasites and other enemies of the moth noticed, the conclusion natu- 
rally arrived at was that the great reduction in the numbers of the 
caterpillars had been effected by the birds. 
When the number of species of birds feeding on hairy caterpillars is 
cousidered, as well as the number of caterpillars eaten by each indi- 
- vidual bird, it becomes evident that birds are an important factor in 
the destruction of hairy caterpillars. It would pay the farmer and 
fruit grower to protect and foster such species for their usefulness in 
this and other ways. 
LIST OF BIRDS THAT FEED ON HAIRY CATERPILLARS. 
The following is a list of the 46 species which, by our observations 
aud dissection, have been proved to feed on hairy caterpillars: 
Yellow-billed Cuckoo, Coccyzus americanus (Linn.). 
Black-billed Cuckoo, Coccyzus erythrophthalmus (Wils.). 
Hairy Woodpecker, Dryobates villosus (Linn.). 
Downy Woodpecker, Dryobates pubescens (Linn.). 
Yellow-bellied Sapsucker, Sphyrapicus varius (Linn.). 
Flicker, Colaptes auratus (Linn.). 
King Bird, Tyrannus tyrannus (Linn.). 
Great-crested Flycatcher, Myiarchus crinitus (Linn.). 
Phebe, Sayornis pheebe (Lath.). 
Wood Pewee, Contopus virens (Linn.). 
