124 BIRDS OF SOUTH DAKOTA 
each locality about blossom time, when insects in vast numbers 
are emerging from the larval state to wreak depredations upon 
shade and fruit trees. 
The great number of Warblers in migration is a constant 
surprise. There are days when the trees seem alive with them, 
and no tree escapes their helpful ministries. With few excep- 
tions they are birds of the tree rather than of the ground. And 
they are birds of the wing; they literally feed on the wing and on 
the run; they are never still; they flit from leaf to leaf and blos- 
som to blossom; they cling to twigs and run along branches; they 
search out insect eggs, feast on insect larvae and swallow mature 
insects indiscriminately ; and they are busy in this way from day- 
light to dark. 
Though called Warblers, they are really not songsters; 
they have no time to sing; they are too busy eating; they sing as 
they go, uttering little snatches of song between mouthfuls. 
These bits of song are never obtrusive, but as much a part of 
open woodlands, groves and orchards as atmosphere or blossoms 
or the humming of bees. 
Warblers are birds of variegated colors, the most conspi- 
cuous being yellow and black, followed by white, blue and chest- 
nut. These colors are usually distributed in large patches or 
prominent stripes on crown, throat, breast, sides, rump, tail and 
wings. Apart from these the general body color of the upper 
parts, while varying much, is apt to be bluish gray, or olive 
green, or a combination of these two. 
636. BLackK AND WHITE WarBLER (Mniotilta varia.) 
A common migrant. Black and white striped, with a 
broad white stripe through the center of the black crown, and 
a narrower white stripe over each eye. It is sometimes called the 
Creeping Warbler from its habit of creeping along tree branches 
like the Brown Creeper. 
645. NasHVILLE WARBLER (J’ermivora rubricapilla rubricapilla.) 
Nests in the Cave Hills Fores‘ Reserve of Harding 
County. 
About four and one half inches in length. Above, olive 
green; below, yellow. Head gray with a brown crown-patch, 
but the latter is not conspicuous in the female. 
