One of these woodpeckers was watched as it moved slowly up a tree trunk. It stopped to knock off a piece of bark with a sidewise (glancing) blow of the heavy bill. This was repeated several times. Then the bird began to drill in earnest and the tapping could be heard by a person more than thirty meters distant. The blows were delivered rapidly, about two per second. Between three and five minutes were required to bore through the bark, in this instance twenty millimeters thick. Then after a few moments of probing the bill was withdrawn and was seen to hold a white larva which was quickly eaten. * * * On one tree thirty-five centimeters in diameter an area of bark thirty by sixty centimeters was punctured completely through by twenty-two holes each leading to the tunnel of a wood-borer. * * * The holes were twelve by twelve millimeters across by twenty deep. It appeared to the observer * * * that many of the still living trees in that locality had been saved from complete destruction by the insects, by the activity of this woodpecker. Manly Hardy wrote to Major Bendire (1895) that, in Maine, “it seems to feed entirely on such wood worms as attack spruce, pine, and other soft-wood timber that has been fire-killed. Specimens are so abundant in such places that I once shot the heads off of six in a few minutes when short of material for a stew.” Some dead pine trees that had been regularly frequented by these woodpeckers, on the Kennard estate, were cut down; and the birds, seeing their favorite trees gone, continued to search for food on the wood piles made from these trees. _Behavior._--Most observers agree that the Arctic three-toed woodpecker is very tame and unsuspicious, working very quietly on a tree trunk for long periods, without moving about much, and allowing a close approach; perhaps, as it lives most of its life in remote northern forests, where men are scarce, it has not learned to fear human beings. Manly Hardy considered it the tamest and stupidest of the woodpeckers found in Maine. Major Bendire (1895) says: “Like the hairy woodpecker, they are persistent drummers, rattling away for minutes at a time on some dead limb, and are especially active during the mating season, in April. I have located more than one specimen by traveling in the direction of the sound when it was fully half a mile away. * * * Its flight is swift, greatly undulating, and is often protracted for considerable distances.” Dr. Lewis says in his notes: “When one bird relieved the other in guarding the cavity, the bird taking over guard duty flew low toward the stub and swerved sharply upward, with widespread tail, to alight near the opening.”