240 LEPIDOPTERA. 



Trouvelot states that the Polyphemus larva constructs its 

 cocoon by drawing the leaves together as a support for the 

 threads, forming the foundation of the cocoon. "This seems 

 to be the most difficult feat for the worm to accomplish, as after 

 this the work is simply mechanical, the cocoon being made of 

 regular layers of silk united by a gummy substance. The silk 

 is distributed in zig-zag lines of about one-eight of an inch 

 long. When the cocoon is made, the worm will have moved 

 his head to and fro, in order to distribute the silk, about two 

 hundred and fifty-four thousand times. After about half a 

 day's work, the cocoon is so far completed that the worm can 

 hardly be distinguished through the fine texture of the wall ; 

 then a gummy, resinous substance, sometimes of a light brown 

 color, is spread over all the inside of the cocoon. "The larva 

 continues to work for four or five days, hardly taking a few 

 minutes of rest, and finally another coating is spun in the 

 interior, when the cocoon is all finished and completely air- 

 tight. The fibre diminishes in thickness as the completion of 

 the cocoon advances, so that the last internal coating is not 

 half so thick and so strong as the outside ones." 



In those moths which spin a thick cocoon, the pupa, a few 

 days previous to its exit, secretes an acid fluid from two glands 

 opening into the mouth. This fluid, according to Mr. L. Trou- 

 velot (American Naturalist, vol. i, p. 33), in his account of the 

 Polyphemus silk-worm, dissolves the hard gummy substance 

 uniting the silken threads, until after the expiration of half an 

 hour, the moth is able to push the fibres aside, and work its 

 way out, without breaking a thread. 



Trouvelot says that the larvae of the Polyphemus moth (and 

 this remark will probably apply to all other Lepidopterous 

 larvae) seem entirely unable to discern objects with their sim- 

 ple eyes, but can distinguish light from darkness. 



In their adult state butterflies and moths take but little food, 

 consisting of honey, though Papilio Turnus, according to a 

 Canadian observer, is attracted to heaps of decaying fish. 



Caterpillars grow very rapidly, and consume a great quantity 

 of food. Mr. Trouvelot gives us the following account of the 

 gastronomical powers of the Polyphemus caterpillar. "It is 

 astonishing how rapidly the larva grows, and one w r ho has no 

 experience in the matter could hardly believe what an amount 



