632 ENTOMOLOGICAL NEWS. [December, 



the past three years examined about 400 cocoons in the hope 

 of finding a certain guide to sex, and without result. Some of 

 my biggest and roundest, baggiest and most "inflated" cocoons 

 gave fine males, while some of the slenderest, longest and 

 'trig"-est cocoons gave females. I have had these cocoons 

 from Illinois, Massachusetts, Vermont and New Hampshire, 

 and a very few from New York. Many of the baggy ones 

 were taken from willow and box-elder trees, eight or ten feet 

 from the ground, while one I took from a tree whose branch I 

 had to pull down with my umbrella in order to reach the 

 cocoon. 



On the other hand, many of the slender, long cocoons were 

 found on low stems of shrubs, while others were high on the 

 box-elders and willows. 



The smallest, thinnest cocoon I had gave a female, the pupa 

 being so large that there was no spare space in the cocoon, and 

 it did not rattle when shaken. 



I have reared many broods of cecropia, and have never had 

 a larva spin a baggy cocoon in captivity, while in these broods 

 the females so outnumber the males that I suspect polygamy ; 

 yet I have this year had a 9 cecropia mate for the second time 

 after ovipositing for three nights. 



The more I stud)' the habits of these creatures, the more 

 variety I find in them the experiences of one year or one 

 brood differing from those of another. 



[A few observations made last spring gave the following 

 results : Eleven ' ' baggy ' ' cocoons disclosed seven males and 

 four females ; twenty- one slender and compact cocoons dis- 

 closed twelve males and nine females. Mr. I. B. Roberts, of 

 Chicago, 111., sends the following result: "Thirty-one 'baggy' 

 cocoons disclosed twenty-five females and six males. The in- 

 flated cocoons were all found in marshy places and nearly always 

 near the ground, and it seems as though the outer part was 

 made as a protection in case of floods. ' ' Miss Soule has proba- 

 bly explained my original observations on the theory of several 

 or individual broods having peculiar characteristics. I do not 

 believe in Mr. Roberts' theory of protection against flood. 



HENRY SKINNER.] 



