Wood Warblers 



303 



FIG. 187. The redstart, one of the warblers that nests in the 

 United States. 



of May, in suitable places in the Middle or Eastern 

 states. In central Ohio, after a warm night with a south 

 wind, about the second week of May, nearly a dozen 

 species of the warbler family may sometimes be observed 

 in a single yard or within a short distance of it. Old 

 oak, thorn-apple, willow, and other trees that harbor 

 insects and their larvae furnish food for these migrants. 

 The food of warblers. Warblers migrate at night and 

 spend much of the day searching the foliage and boughs for 

 insects or capturing them on the wing. They are nimble 

 little birds, and many of the insects they eat are too 

 small to be noticed by other birds. But small insects, if 

 sufficiently numerous, may do as much damage as larger 

 kinds. Professor Herbert Osborn has shown that one 

 acre of pasture frequently contains a million leaf hop- 

 pers, which consume as much grass as a cow. By de- 

 stroying these tiny insects as well as grasshoppers, the 

 Maryland yellowthroats are useful in pastures. Yellow 

 warblers eat measuring worms, tent caterpillars, bark 

 beetles, and other injurious insects. All the birds of 

 this interesting family are beneficial. 



