At time for emergence the moth bursts the pupa case, which is extremely thin and papery compared with the cases of burrowing species.  We know by the wet moth that liquid is ejected, although we cannot see the wet spot on the top of the inner case of Cecropia as we can with Polyphemus, that does not spin the loose outer case and silk nest.  From here on the moths emerge according to species.  Some work with their mouths and fore feet.  Some have rough projections on the top of the head, and others little sawlike arrangements at the bases of the wings.  In whatever manner they free themselves, all of them are wet when they leave their quarters.  Sometimes the gathered silk ends comb sufficient down from an emerging Cecropia to leave a terra cotta rim around the opening from which it came; but I never saw one lose enough at this time to disfigure it.  On very rare occasions a deformed moth appears.  I had a Cecropia with one wing no larger than my thumb nail, and it never developed.  This is caused by the moth sustaining an injury to the wing in emergence.  If the membrane is slightly punctured the liquid forced into the wing for its development escapes and there is no enlargement.

Also, in rare instances, a moth is unable to escape at all and is lost if it is not assisted; but this is precarious business and should not be attempted unless you are positive the moth will die if you do not interfere.  The struggle it takes to emerge is a part of the life process of the moth and quickens its circulation and develops its strength for the affairs of life afterward.  If the feet have a steady pull to drag forth the body, they will be strong enough to bear its weight while the wings dry and develop.

All lepidopterists mention the wet condition of the moths when they emerge.  Some explain that an acid is ejected to soften the pupa case so that the moth can cut its way out; others go a step farther and state that the acid is from the mouth.  I am extremely curious about this.  I want to know just what this acid is and where it comes from.  I know of no part of the thorax provided with a receptacle for the amount of liquid used to flood a case, dampen a moth, and leave several drops in the shell.

As soon as a moth can find a suitable place to cling after it is out, it hangs by the feet and dries the wings and down.  Long before it is dry if you try to move a moth or cause disturbance, it will eject several copious jets of a spray from the abdomen that appears, smells and tastes precisely like the liquid found in the abandoned case.  If protected from the lightest touch it will do the same.  It appeals to me that this liquid is abdominal, partly thrown off to assist the moth in emergence; something very like that bath of birth which accompanies and facilitates human entrance into the world.  It helps the struggling moth in separating from the case, wets the down so that it will pass the small opening, reduces the large abdomen so that it will escape the exit, and softens the case and silk where the moth is working.  With either male or female the increase in size is so rapid that neither could be returned to their cases five minutes after they have left them.