THE STATE ENTOMOLOGIST. 105 



this country. The following are some of Mr. Trouvelot's reasons, as com- 

 municated to me, for j)referring Polyphemus to Cecropia : 



1st. The silk fibre spun by the latter is not so strong nor so glossy as 

 that of the former. 2ndly. The cocoon of the latter being double, pointed, 

 and open at one end, makes it unfit to reel, as the water of the bath in fill- 

 ing the cocoon would sink it to the bottom, a very unfavorable circum- 

 stance, since it would cause the fibres of the different cocoons to entangle 

 and break every moment. 3rdly. The larva of Cecropia is a very delicate 

 worm to raise, it does not suffer handling, and when once feeding on a given 

 species of plant, it does not readih^ bear changing to another, or even to a 

 variety of the same plant. -Ithly. It has the misfortune to be more gener- 

 ally attacked by birds and parasites, four-fifths of them being thus sacrificed. 

 in a state of nature. 



I entirely concur in the first two reasons given, but since, as 1 shall 

 presently show, a method has been devised for unwinding cocoons naturally 

 open, such as those of cynthia and Cecropia, the second objection loses much 

 of its force. As to the last two objections, though they undoubtedly apply 

 in Massachusetts, where Mr. Trouvelot made his experiments, they will not 

 hold true in the West; for I have always been more successful with in-door 

 broods of Cecropia than of Polyj^hemus, and with us the latter is fully as 

 much subject to parasites as the former, as might have been inferred from 

 its conij^arative scarcity. I have also learned from several correspondents 

 in the Atlantic States that whereas it was formerly almost imjiossible to raise 

 a single specimen of Cecropia to the perfect state, they now have no ditii- 

 culty in rearing any number. 



In the month of May, in the latitude of St. Louis, and earlier or later the 

 farther north or south we go, our Cecropia moth issues from its cocoon, and 

 there can be no more beautiful sight imagined, than one of these gigantic fresh- 

 born moths with all its parts soft and resplendent. The unintiated Avould 

 marvel how such an immense creature had escaped from the small cocoon 

 which remains at its side, retaining the same form which it always had, and 

 showing no hole through which the moth could escape. The operation — so 

 interesting and instructive — can be witnessed by any one who will take the 

 trouble to collect a few of the cocoons and place them in some receptacle 

 Svhich has sufficiently rough sides to admit of the moth's crawling up, to 

 hang its heavy body and wings while they dry and expand. The caterpillar 

 has the wonderful foresight to spin the upper or anterior end of its cocoon 

 very loosely, and when the moth is about to issue it is still further aided in 

 its efforts by a fluid secreted during the last few days of the chrysallis state, 

 and which is a dissolvent of the gum which so firmly unites the fibres of the 

 cocoon. This fluid is secreted from two glands, which open into the mouth, 

 and as soon as the chrysalis skin is split open on the back, by the restless 

 movements of the moth within, the fluid flows from the mouth and wets the 

 end of the cocoon, dissolving the gum and softening the silk to such an 

 extent, that by repeated contractions and extensions of the body, the moth 

 is at last enabled to separate the fibres, and to thrust out its head and unbend 



