28 THE CANADIAN ENTOMOLOGIST. 



NOTES ON BOMBYCID.^. 



BY FREDERICK CLARKSON, NEW YORK. 



The habits of insects present an attractive and fruitful field of dis- 

 covery, illustrating in many remarkable ways their peculiar instincts 

 governed by heredity, and more or less conditioned by environment. The 

 power which we call instinct, controlling the habits of insects, has a regu- 

 larity of action governed by ordinary conditions, but there are frequent 

 manifestations of adaptation to circumstance, as conspicuous in the several 

 orders of insects as in the various races of mankind. The extraordinary 

 condition can only be regarded as an obstruction to the usual law that 

 governs instinct, and compels the creature to conform to the changed 

 surroundings. The larv^ of Bombyx viori if crowded for space at the 

 time of pupation will associate to the number of three or four in spinning 

 the one cocoon which covers them. The larvae of Samia cynthia under 

 like environment present a similar variation of habit by spinning interior 

 sections one above the other in the silk-lined leaf constituting the one 

 envelope, so that outwardly it has the appearance of a long, single cocoon. 

 The marked feature of this dual cocoon is, that while ordinarily the place 

 of escape for the imago is at the upper end of the cocoon, the inhabitant 

 of the lower section emerges at the lower end of the cocoon, from the lower 

 end of its section. The Cynthia worms occasionally, from like necessity, 

 will, to the number of two, spin a cocoon in common and undergo trans- 

 formation in the one interior section. I have collected the past season 

 very diminutive cocoons of F. cecropia and S. cynthia., the former measur- 

 ing one and one-half inches long by one-half inch in diameter ; the in- 

 terior section three-quarters of an inch long by three-eighths of an inch in 

 diameter; the latter was spun on a leaf one and one-half inches long, the 

 cocoon rather less by three-eighths of an inch in diameter. The cocoons 

 contained the larva dead and in a dried condition. 



From a cocoon of P. cecropia I have obtained a very small male, 

 measuring scarcely four inches in expanse of wing. The kidney-shaped 

 spots on secondaries are reversed from their usual position, the pointed 

 end being directed towards the abdominal or inner margin, instead of as 

 commonly to the exterior margin. The wavy white line, bordered with 

 black, on the exterior margin of the primaries, which is usually more 

 or less pointed into the adjoining lilac, is in this specimen a line corres- 

 ponding in form with that of the margin of the wing. 



