Each moth I ever have seen emerge has been wet and the empty case damp inside.  I have poured three large drops of pinkish liquid the consistency of thin cream from the abdominal rings of a Regalis case.  Undoubtedly this liquid is ejected by the moth to enable it to break loose from and leave the case with its delicate down intact.  The furry scales of its covering are so loosely set that any violent struggle with dry down would disfigure the moth.

Among Cecropia and its Attacine cousins, also Luna, Polyphemus, and all other spinners the process is practically the same, save that it is much more elaborate; most of all with Cecropia, that spins the largest cocoon I ever have seen, and it varies its work more than any of the others.  Lengthwise of a slender twig it spins a long, slim cocoon; on a board or wall, roomier and wider at the bottom, and inside hollow trees, and under bridges, big baggy quarters of exquisite reddish tan colours that do not fade as do those exposed to the weather.  The typical cocoon of the species is that spun on a fence or outbuilding, not the slender work on the alders or the elaborate quarters of the bridge.  On a board the process is to cover the space required with a fine spinning that glues firmly to the wood.  Then the worker takes a firm grip with the anal props and lateral feet and begins drawing out long threads that start at the top, reach down one side, across the bottom and back to the top again, where each thread is cut and another begun.  As long as the caterpillar can be seen through its work, it remains in the same position and throws the head back and around to carry the threads.  I never thought of counting these movements while watching a working spinner, but some one who has, estimates that Polyphemus, that spins a cocoon not one fourth the size of Cecropia, moves the head a quarter of a million times in guiding the silk thread.  When a thin webbing is spun and securely attached all around the edges it is pushed out in the middle and gummed all over the inside with a liquid glue that oozes through, coalesces and hardens in a waterproof covering.  Then a big nest of crinkly silk threads averaging from three to four inches in length are spun, running from the top down one side, up the other, and the cut ends drawn closely together.  One writer states that this silk has no commercial value; while Packard thinks it has.  I attach greater weight to his opinion.  Next comes the inner case.  For this the caterpillar loosens its hold and completely surrounds itself with a small case of compact work.  This in turn is saturated with the glue and forms in a thick, tough case, rough on the outside, the top not so solidly spun as the other walls; inside dark brown and worn so smooth it seems as if oiled, from the turning of the caterpillar.  In this little chamber close the length and circumference of an average sized woman’s two top joints of the first finger, the caterpillar transforms to the pupa stage, crowding its cast skin in a wad at the bottom.