HOW BIRDS AFFECT THE ORCHARD. 293 
especially subject to their attacks. Ants protect these plant lice from 
harm, and, when the plant on which they are feeding is exhausted, 
carry them to fresh pastures, and in some cases actually build shelters 
over them. Besides destroying the ants, the downy woodpecker eats 
many of the plant lice. 
Again, when the woodpecker has, by its keen sense of hearing, 
located the larva of a wood-boring beetle in a tree, and dislodged it 
with the aid of the sharp-edged chisel and probe, there is much likeli- 
hood that the next 
time it visits the tree 
it will find a colony 
of ants snugly estab- 
lished in the burrow 
of the defunct grub, 
whose somewhat lim- 
ited quarters they are 
extending in every 
direction. It now 
brings to bear upon 
the ants the same ap- 
paratus it used in the 
case of the grub, and 
they are soon drawn: Fic. 35.—Special development of tongues of woodpeckers: a, skull of 
out and devoured. flicker (Colaptes aurutus), showing root of tongue extending to tip 
F thes t of bill (after Lindahl); b, head of hairy woodpecker (Dryobates 
rom ese wo villosus), showing root of tongue curving around eye (after Audu- 
sources are obtained bon). 
the ants that are found in the food of this bird, and that constitute 23 
per cent of that food. In both cases the insects are harmful, and the 
woodpecker stops the injury and benefits the tree. 
Of the food of the downy woodpecker, 13 per cent consists of wood- 
boring coleopterous larvx, insects that do an immense amount of dam- 
age to fruit and forest trees, and are, as stated, protected from the 
attacks of ordinary birds by their habit of burrowing in trees. Besides 
the grubs taken from within the wood, the woodpecker eats many of 
the parent insects from whose eggs these grubs are hatched. It also 
destroys numerous other species that live upon the foliage and bark. 
Caterpillars, both those that bore into the tree and those that live upon 
the leaves, constitute 16 per cent of its food, and bugs that live on 
berries and give to them such a disagreeable taste form a considerable 
portion of its diet. Bark lice or scale insects (Coccide), pests of the 
worst description, are also eaten by this bird, and to an extent that is 
surprising when their minute size is considered. 
Harry wooprPecKER.—The hairy woodpecker (Dryobates villosus, fig. 
36) subsists on food that is similar in general to that of the downy; 
and although it does not eat quite so many ants, it destroys more 
