When they are ready to leave the water they make their way to the shore, and, clinging to some convenient tree trunk or building, they shed their nymph skins. I have seen trees and buildings on the banks of the St. Lawrence river literally covered with these cast skins. In the early morning in June and July one may watch the molting process, the unfolding of the gauzy wings, and the unsheathing of the long filaments. ([Fig. 53.])
Do not believe that May-flies are harmful. They are sometimes too numerous for comfort at summer resorts where myriads of them swarm about the lights; but stories of their stinging and biting are entirely without foundation. They are short-lived in the adult stage. The name of the family to which they belong, Ephemeridæ, suggests their ephemeral existence. It is of these that poets have sung.
Stone-fly nymphs, also, cling closely to the flat stones. The cast skins of these are frequently found on the banks of streams. They resemble the May-fly nymphs but can be identified by a comparison with these illustrations. ([Fig. 54].)
Sometimes on the very brink of a cataract one will see what appear like patches of loose black moss. Strangely enough, these are the larvæ of black-flies, related to the terrible black-fly of the north woods. The black-fly larvæ can live only in the swiftest water. There they pass through their transformations and succeed in emerging into their aërial stage, in spite of the rushing current.
Fig. 53. The May-fly sheds its nymph skin. (Twice natural size.)
All these things and many more are seen by those who frequent the water brooks. Observers cannot tell all they see, for some things are too deep for words. They can and do say to one and all, "Come, let us visit the brook together. The water and all that dwell in it and round about, invite us and make us welcome."
Fig. 54. Stone-fly, showing one pair of wings. The lower figure is a nymph. (Twice natural size.)