Farmers are prone to look upon woodpeckers with suspicion. When the birds are seen scrambling over fruit trees and pecking holes in the bark, it is concluded that they must be doing harm. Careful observers, however, have noticed that, excepting a single species, these birds rarely leave any conspicuous mark on a healthy tree, except when it is affected by wood-boring larvæ, which are accurately located, dislodged, and devoured by the woodpecker. Two of the best-known woodpeckers, the hairy woodpecker[55] (fig. 20) and the downy woodpecker,[56] including their races, range over the greater part of the United States. They differ chiefly in size, their colors being practically the same. The males, like those of many other woodpeckers, are distinguished by a scarlet patch on the head. An examination of many stomachs of these two species shows that from two-thirds to three-fourths of the food consists of insects, chiefly noxious kinds. Wood-boring beetles, both adults and larvæ are conspicuous, and with them are associated many caterpillars, mostly species that burrow into trees. Next in importance are the ants that live in decaying wood, all of which are sought by woodpeckers and eaten in great quantities. Many ants are particularly harmful to timber, for if they find a small spot of decay in the vacant burrow of a wood borer, they enlarge the hole, and, as their colony is always on the increase, continue to eat away the wood until the whole trunk is honeycombed. Moreover, they are not accessible to birds generally, and could pursue their career of destruction unmolested were it not that the woodpeckers, with beaks and tongues especially fitted for such work, dig out and devour them. It is thus evident that woodpeckers are great conservators of forests. To them more than to any other agency we owe the preservation of timber from hordes of destructive insects. [55] _Dryobates villosus._ [56] _Dryobates pubescens._ [Illustration: Fig. 21.—Flicker. Length, about 12½ inches. ]