_Eggs._--Four seems to be the usual number of eggs laid by this woodpecker; I can find no record of either more or fewer in complete sets. The eggs are ovate, pure white, and only moderately glossy. The measurements of 43 eggs average 23.32 by 18.01 millimeters; the eggs showing the four extremes measure =25.5= by 18.2, 23.8 by =19.6=, and =20.1= by =15.0= millimeters. _Young._--The period of incubation is said to be about 14 days, and it is shared by both sexes. Both parents feed and care for the young, even after the young leave the nest, as family parties are seen traveling about together in summer. _Plumages._--The nestlings are probably hatched naked and blind, as with other woodpeckers, but the juvenal plumage is acquired before the young leave the nest. In the juvenal plumage, the young male is similar to the adult male, but the yellow crown patch is smaller and less sharply defined; the upper parts are duller, brownish black instead of sooty black; the flanks are more heavily and more extensively banded, or spotted, with sepia instead of clear black; the white of the throat and breast is tinged with pale buffy. The juvenal female is similar to the young male, but the yellow crown patch is smaller, and the amount of yellow in it is very variable, sometimes only a few scattered feathers and sometimes a well-defined, clear patch. This plumage is worn at least through August and probably well into fall. The only molting adults I have seen were taken in August. _Food._--The feeding habits of the American three-toed woodpecker are almost identical with that of the Arctic three-toed. Prof. F. E. L. Beal (1911) says: The largest item with both species is wood-boring coleopterous larvae. These amount to 64.25 percent with _arcticus_ and 60.66 with _americanus_. Caterpillars, which in this case are mostly wood-boring species, amount to 12.88 and 14.45 percent for the two birds respectively. The total of wood-boring larvae, including both caterpillars and beetles, is, 77.13 percent for _arcticus_ and 75.11 percent for _americanus_, or more than three-fourths of the food of both species. * * * Fruit skins were found in only one stomach of _americanus_ and mast in but one stomach of _arcticus_. Cambium was found in 10 stomachs of _arcticus_ and 8 of _americanus_. This indicates that these birds do some pecking at the bark of living trees for other purposes than getting insects, but no complaints have yet been made, from which we infer that little or no damage is done; in fact the amount contained in the stomachs is not large a little less than 10 percent.