1911] Ran — Cecropia Cocoons 169 



The proportion of fluffy cocoons to compact ones was as follows : 



The figures show that in 1910 the baggy cocoons occurred in 

 the proportion, roughly, 1:4, and in 1911, 1: 6. Hence they can- 

 not be called rare in this locality. 



The records kept at the time of the emergence of the imagines 

 yield the following data: 



Females. Dead. 

 22 



40 15 



This shows that only a small per cent., if any, of the pupae may 

 have been parasitized. It further shows that sex plays no part in 

 determining the form of the structure, but that individuals of 

 either sex are quite capable of spinning cocoons of this character. 



The tightly woven cocoons are so well known that any descrip- 

 tion would be quite superfluous. In the fluffy ones all degrees of 

 size were found; some only slightly larger than the ordinary com- 

 pact cocoon and a little more loosely woven. From this they 

 ranged to the size illustrated herewith. This photograph gives 

 the exact size of the largest one found. Most of them, however, 

 were just about one half this size, and varied much in shape. 



It was suggested that these individuals must represent a sep- 

 arate and distinct race. So when the female emerged from this 

 large cocoon, it was bred with a male of like character, with the 

 purpose of learning whether or not the tendency to fluffy cocoon 

 spinning might be an inherited characteristic. It was, however, 

 unfortunate that on account of the lack of proper facilities, the 

 larvae soon died. 



But along with this experiment, some interesting data on ovi- 

 position were gathered. In the first place, the female was an 

 exceptionally large one, the expanse of the forewings measuring 

 20 cm. It mated before daybreak. May 18, two days after emerg- 

 ing, and remained in copula the normal length of time, about 

 twenty -four hours. By noon. May 19, it had deposited 358 eggs. 

 For the next two days, no eggs were laid; on the 22d and 23d, 44;, 



