404: GROTE — COCOON OF TELEA POLYPHEMUS. [Oct. 3, 



promethea. C. angultfera, which seems the older form of Cal- 

 iosainia, has not acquired the habit. The most generalized group' 

 of the Attacides (= Saturnides Boisd. 1840, Saturnina Dyar, 

 1894), namely the Aglians or Citheronians, make either a slight 

 cocoon on the surface or none at all, entering the ground to pupate 

 like the Hawk Moths. In the Emperor Moths, specialization of 

 the pupal protection or envelope is evidenced by its growing com- 

 plexity. Telea is one of the genera using a leaf as a wrapper or 

 external support for the cocoon. Neither Samia or Saiurnia have 

 this habit, spinning against stems or branches. 



Another advantage arising from the spinning of the cocoon on 

 the tree which served as a food-plant for the larva would be that 

 the perilous descent of the latter down the trunk, to spin in fallen 

 leaves on the ground, is obviated. The habit of descending the 

 tree to pupate appears to be general, and I have observed it with 

 Actias luna, which spins a thinner, more papery cocoon than its 

 more specialized ally, Telea polyphemus ; the cocoon of the latter 

 could probably resist injury to the chrysalis in falling with the leaf. 



The specimen of Telea here under observation is a remarkably 

 large and heavy one, so that it might be thought possible the larva 

 hesitated to trust to the leaf alone, and hit upon the plan of fasten- 

 ing itself by a silken rope. As against this idea might militate the 

 fact that the forms which habitually attach the cocoon in this 

 manner are relatively light-bodied species, in comparison with their 

 enormous wings. The heavy-bodied species of Samia and Telea 

 spin no attachment. This latter seems feebly indicated in the 

 cocoon of Rothschildia zacobcBCB. However, the nature of the food- 

 plant may besides hasten or retard the acquirement of the custom, 

 which seems to grow out of the use of a leaf as an outer wrapper, 

 and to correlate with the arboreal habit of the moth. 



Whatever opinion we may form regarding the case in point, it is 

 evident that the spinning of the pedicel is not only an advance or 

 a specialization upon an earlier plan of cocoon-making, but that it 

 can be suddenly put forth on occasion by the more generalized or 

 primitive tree-feeding Attacids, as is now demonstrated. And from 

 this instance we may certainly conclude that the habit of spinning 

 a stem to the cocoon has arisen singly, with the leaf-spinning indi- 

 vidual, called forth by whatever exciting cause. Out of this 

 individual departure a custom and habit for the species at large has 

 been most probably secondarily developed, since it clearly proved 



