As one might expect from the short seasons of the far northern regions in which this butterfly lives, there is only one brood each year. In consequence the adult butterflies live a long time. Coming from the chrysalis generally the first weeks in August, they remain upon the wing a month or more before they go into hibernation. They come from their winter quarters in May and commonly continue alive until late in June. Thus it is evident that many of these butterflies must live at least ten months as adults, an extraordinary longevity for one of these frail creatures. The caterpillars are known to feed upon the foliage of several kinds of plants. These include alder, currant, gooseberry, willow, and black birch, the last two named apparently being those most often chosen. Mr. S. H. Scudder called attention to the fact that these butterflies are able to make a slight clicking noise as they start into flight. He described his experience in these words: "Starting up a pair just at my feet on the Mt. Washington carriage road one day, I stopped abruptly to see whether they would settle again. After flying a few yards away to escape the cause of their disturbance, one turned back and dashed straight at my face, turning only when within three or four inches of my nose, and then suddenly whisked off with a distinct click as it did so, snapping its fingers, as it were, in my very face. There was no sort of doubt about this click, though if it had not been made so close at hand it would probably not have been heard. But other butterflies in the tropics have long been known to emit sounds like this, which can be heard at a considerable distance; others, including some of our own butterflies, are known to produce a rustling sound by the rubbing of one wing upon another; and movements of one sort and another have been so often observed, as of the opposite rubbing of the erect wings in most Lycaenids, and the tremulous agitation of the wings in many different sorts when excited, as to leave little doubt that sounds made by themselves and for the advantage of warning their brethren play a not unimportant part in the lives of butterflies." [Illustration: _See page 233_ MONARCH BUTTERFLY IN RESTING POSITION] [Illustration: _Photograph by Miss J. Brooks_ _See pages 17, 232_ FLASHLIGHT PHOTOGRAPH OF MONARCH OR MILKWEED BUTTERFLIES IN MIGRATION] [Illustration: THREE ANGLE-WINGS: UPPER SURFACE The American Tortoise-shell (_see page 182_) The Red Admiral (_see page 160_) The Violet-tip (_see page 150_)] [Illustration: THREE-ANGLE WINGS: LOWER SURFACE The American Tortoise-shell (_see page 182_) The Red Admiral (_see page 160_) The Violet-tip (_see page 150_)] [Illustration: _From a drawing by W. I. Beecroft_ _See page 163_