As soon as the young hatch the female begins feeding them. I have seen no evidence of regurgitation. She thoroughly crushes caterpillars, etc., between her mandibles before giving them to the young. Their food for the first day consists of small insects, soft white grubs and a large number of half inch, smooth, green caterpillars, which are found on hemlock trees. From the second to the eighth day their diet consists chiefly of small green caterpillars, insects, white grubs and an occasional may-fly or gray and cream colored caterpillar without spines. On the ninth and tenth day their diet still includes white grubs and green caterpillars, but dragon flies and may-flies are the chief staples. Slugs, winged ants, white cabbage butterflies and moths are also on the menu. From the time the young hatch until they are five days old the parents swallow the faecal sacs. After that they carry them away from the nest and place them on the branches of neighboring trees--frequently using dead branches. She gives a detailed account of the development of the young and their manner of leaving the nest naturally on the tenth day. During the 6 days when she thought it safe to handle them without driving them out of the nest too soon, one increased in weight from 22 grains to 141, and another from 24 to 147 grains. _Plumages._--The sexes differ slightly in the juvenal plumage. The young male is olive-brown above; the wings are blackish, the primaries edged with bluish-leaden-gray; the wing coverts, secondaries, and tertials are margined with olive-green, and there is a white patch near the base of the primaries, as in the adult; the tail is much like that of the adult; the under parts are brownish, tinged with yellowish on the throat and abdomen; the lores and two submalar streaks are dusky, and the superciliary stripe is yellowish white. The young female is similar, but has dull brown wings and tail with greenish instead of bluish edgings, and the white area in the primaries is smaller, more dingy and sometimes obscure. A partial postjuvenal molt occurs in late July and August involving the contour plumage and the wing coverts but not the rest of the wings or the tail, producing a first winter plumage in which the sexes become decidedly differentiated and not very different from the adults at that season. This is one of the few wood warblers in which the fall plumage is very much like the spring dress. In the young male the blue of the upper parts is not as clearly blue as in the adult; the feathers of the back are faintly edged with olive-green, those of the black throat veiled with dull whitish, and the abdomen is tinged with yellowish. The young female differs from the fall adult in being greener above, without bluish tinge, and more buffy or yellowish below.