When the time of its transformation draws near, the larva, in which stage the insect passes the greater part of its existence, works its way up towards the surface, oftentimes in a very circuitous manner, for local changes make it necessary for it to bore through hard woods and between stones well beaten down. The burrow which it thus produces is cylindrical, about five-eighths of an inch in diameter, and firmly cemented and varnished so as to be water-proof. The upper portion, to the extent of five or six inches, is empty, and serves as a habitation till the period of its exit arrives, while the lower is filled with earthy matter removed by the insect in its progress. In this cell it remains during several days, ascending to the top for the benefit of the sunshine and air when the weather is auspicious, even venturing to peep forth occasionally, but descending on the occurrence of cold or wet weather. But when the favorable moment to leave their subterranean retreats arrives, the Cicada-grubs, or more properly pupæ, for such they are now to be considered, although they still retain something of the grub-like form, issue from the ground in great numbers as evening draws on, crawl up the trunks of trees, the stems of herbaceous plants, or on to whatever is convenient, which they grasp securely with their claws. After resting awhile, their skins, which have become dry and of an amber color, are by repeated exertions rent along the back, and through the slit formed the included Cicada pushes its head and body, and withdraws its wings and legs from their separate cases, and, crawling to a short distance, leaves its empty pupa-case fastened to the tree. At first the wing-covers and wings are small and opaque, but in a few hours they acquire their natural size and shape. It is not, however, for three or four days that the muscles harden sufficiently for them to assume their characteristic flight. The males make their appearance some days in advance of the females, and also disappear sooner. During several successive nights the pupæ continue to issue from the ground, and in some places, as was the case in May of 1868, when these insects appeared in great numbers in the vicinity of Philadelphia, the whole surface of the soil was made by their operations to assume a honey-combed appearance. [Illustration: DOME-LIKE HOUSE OF CICADA. Longitudinal Section Showing Pupa in Two Positions.]