THE AMERICAN ENTOMOLOGIST. 



99 



posud of the same kiiul of silk, but closely 

 woven liko that of the common Silk-worm. 

 Inside this cocoon will be found tlie large 

 brown chrysalis [FIk. en.] 



(Fig. CI). The co- 

 coon of the large Po- 

 lyphemus Moth (see 

 Ajikrican Entomo- 

 logist, Volume I, 



No. 7), which has c:olo,-Light brown. 



been called by Mr. L. Trouvelot, of Med- 

 ford, Massachusetts, the "American Silk- 

 worm," is rounded, and the silk is very 

 closely and compactly woven : and though that 

 of our Cecropia is not as valuable for utilitarian 

 purposes, yet we liave not a doubt but it will 

 some day be propagated for the silk which it 

 produces; and though it may not laj' claim to 

 the national title of THE American Silk-worm, 

 it will nevertheless rank as second best, among 

 those which are indigenous to this country. 



The following are some of Mr. Trouvelot's 

 reasons, as conmiuuicated to us, for prefer- 

 riiig Polyphemus to Cecropia: 1st. The silk 

 fibre spun by the latter is not so strong nor so 

 glossy as that of the former. 2udly. 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 filling the cocoon would sink it to 

 the bottom, a very unfavorable circumstance, 

 since it would cause the fibres of the different 

 cocoons to entangle and break every moment, 

 ordly. The larva of Cecropia is a very delicate 

 worm to raise, it does not sufier handling, and 

 when once feeding on a given species of plant, 

 it does not readily bear changing to another, or 

 even to a variety of the same plant. 4thly. It 

 has the misfortune to be more^enerally attacked 

 by birds and parasites, four-fifths of them being 

 thus sacrificed, in a state of nature. We entirely 

 concur in the first two reasons given, though 

 until the silk of Polyphemus has been more suc- 

 cessfully reeled off than heretofoi-e, the second 

 objection loses much of its force, since our own 

 experiments would indicate that they both have 

 to be carded. As to the last two objections, 

 though they undoubtedly apply in Massachu- 

 setts, where Mr. Trouvelot made his experi- 

 ments, they will not hold true iu the West: for 

 we have always been more successful with in- 

 door broods of Cecropia than of Polyphemus, 

 and with us the latter is fully as much subject 

 to parasites as the former, as might have been 

 inferred from its comparative scarcity. 



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 resplen- 

 dent. The uninitiated would 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 tvho will take the 

 trouble to collect a few of the cocoons and place 

 them in some receptacle which 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 won- 

 derful 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 efibrts by a fluid secreted during the last 

 few days of the chrysalis 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 moutli 

 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 its front legs ; after which it rapidly 

 draws out the rest of its body, the mouth of 

 the cocoon afterwards closing, by the natural 

 elasticity of the silk. At this moment the body 

 of the motli is much swollen and elongated, 

 the wings are small, folded, and pad-like, and 

 the whole insect is soft and moist; but attach- 

 ing itself to the first object at hand, where it 

 can hang its heavy body and clumsy wings, 

 the latter become expanded in about twenty 

 minutes, and the superabundant fluids of the 

 body sufficiently evaporate in a few hours to 

 enable the insect to take wing. 



The eggs of the Cecropia Moth are U.tiO inch 

 long, sub-oval, flattened, and of a pale cream- 

 color, shaded with light brown, and they arc 

 deposited in small patches on the plants which 

 are to form the food of the future larvse. Tl)ey 



list oi-casion that iircsfiUeil: I'oi- hi- linally hecfimu t-utii-ely 

 auiviuceil that sucli ii fluid is secreted, and-lVeely ackuowl- 

 ■dged liis former error, as lie was always ready to do in such 



