102 Journal New York Entomological Society. [Voi. xv. 



in crossing the two species. With a stock of two thousand cocoons 

 and the aid of my sister I thought some results could be had. 



From the start we found that there was a great difference in the 

 desire to mate in the two species and also in individuals of the same 

 species. The promethia J^ was generally quite willing and even 

 anxious to take a cyiithia ? for wife but she was so averse to a mixed 

 marriage, that the attempt, although persisted in by \h^ promethia S', 

 was usually a failure and the eggs infertile. It was interesting to 

 watch the cynthia ? attempt to get rid of t\\e. p?-omethia, by contract- 

 ing the abdomen, more especially the tip which was entirely retracted 

 and the body was meanwhile turned from side to side until the 

 claspers of the promethia slipped off. The promethia would try it 

 again and again with the same result, and it was only in a few cases 

 that the attempt was successful and the eggs fertile. In a number of 

 cases the mating was evidently successful but the cynthia would refuse 

 to lay eggs and hang to the bag with her abdomen retracted to its 

 smallest compass until death, unless a cynthia (^ was introduced when 

 mating readily took place and egg laying would begin. 



In my experience I have never found cynthia 9 willing to mate 

 with two males so that remating with cynthia after promethia is 

 interesting. 



In these two crosses the eggs were typical cynthia and the larvae, 

 as Miss Soule states, were also cynthia except that mine seemed to 

 have a tendency to yellowish cream color ; but this may have been due 

 to rearing in jars. 



The silk made by these larvae was typical cynthia silk. The 

 cocoons of the singly mated ones were rather smaller than normal 

 cynthia but the cocoons of the twice mated females were about normal 

 in size to cyiithia. Both, to me, presented the appearance and shape 

 of true cynthia cocoons in all particulars, and the larvae had the same 

 habit of spinning a long stem, often a foot long, where occasion 

 required it. The opening of the cocoon was also arranged and had 

 the appearance, as in cynthia. Should my lot of cocoons of these two 

 crosses be mixed with true cynthia ones I doubt if any one could 

 separate them. This difference from the observations of Miss Soule 

 may be accounted for by their feeding on Ai/anthus. 



The real interest in the series of crosses came from some matings 

 oi promethia ? with cynthia S'. In these crosses we had the same 

 difficulty of the female not laying until remated with a male of her 



