It is generally supposed that the spray thrown by a developing moth is for the purpose of attracting others of its kind.  I have my doubts.  With moths that have been sheltered and not even touched by a breath of wind, this spray is thrown very frequently before the moth is entirely dry, long before it is able to fly and before the ovipositor is thrust out.  According to my sense of smell there is very little odour to the spray and what there is would be dissipated hours before night and time for the moths to fly and seek mates.  I do not think that the spray thrown so soon after escape from cocoon or case is to attract the sexes, any farther than that much of it in one place on something that it would saturate might leave a general `mothy’ odour.  Some lepidopterists think this spray a means of defence; if this is true I fail to see why it should be thrown when there is nothing disturbing the moth.

Many of the spinning moths use leaves for their outer foundation.  Some appear as if snugly rolled in a leaf and hanging from a twig, but examination will prove that the stem is silk covered to hold the case when the leaf loosens.  This is the rule with all Promethea cocoons I ever have seen.  Polyphemus selects a cluster of leaves very frequently thorn, and weaves its cocoon against three, drawing them together and spinning a support the length of the stems, so that when the leaf is ready to fall the cocoon is safely anchored.  When the winter winds have beaten the edges from the leaves, the cocoon appears as if it were brown, having three ribs with veins running from them, and of triangular shape.  Angulifera spins against the leaves but provides no support and so drops to the ground.  Luna spins a comparatively thin white case, among the leaves under the shelter of logs and stumps.  Io spins so slightly in confinement that the pupa case and cast skin show through.  I never have found a pupa out of doors, but this is a ground caterpillar.

Sometimes the caterpillar has been stung and bad an egg placed in its skin by a parasite, before pupation.  In such case the pupa is destroyed by the developing fly.  Throughout one winter I was puzzled by the light weight of what appeared to be a good Polyphemus cocoon, and at time for emergence amazed by the tearing and scratching inside the cocoon, until what I think was an Ophion fly appeared.  It was honey yellow, had antennae long as its extremely long body, the abdomen of which was curved and the segments set together so as to appear notched.  The wings were transparent and the insect it seems is especially designed to attack Polyphemus caterpillars and help check a progress that otherwise might become devastating.

Among the moths that do not feed, the year of their evolution is divided into about seven days for the life of the moth, from fifteen to thirty for the eggs, from five to six weeks for the caterpillar and the remainder of the time in the pupa stage.  The rule differs with feeding moths only in that after mating and egg placing they take food and live several months, often until quite heavy frosts have fallen.