REPORT OF THE ENTOMOLOGIST. 273 



284 immature ones. After tliat date I dissected many females, but 

 found only immature eggs. 



It is difficult to say how long this insect exists in the adult state; 

 doubtless the time varies greatly with the season. Moths of the third 

 and fourth broods die in confiuenient within five days after their exclu- 

 sion from the pupa, while, as we shall show later, those of the last brood 

 remain alive several months. 



The number of broods of this insect in a single season is also some- 

 what difficult to determine. For not only does the earliest brood ap- 

 pear at different times in different sections of the cotton belt, but in the 

 same locality different individuals of the first brood were found to vary 

 in age nearly two weeks. As a result of this variation during the latter 

 part of the season, examples of all stages were found at the same time 

 in the same field. Still a large proportion of the cotton-worms in a 

 given locality undergo their transformations at nearly the same time; so 

 that broods sufficiently well marked for our purpose have been ob- 

 served. And we conclude that in those sections in which we believe the 

 moth to hibernate, there are each year at least six broods. By the 1st 

 of September of the present year (1879) larvae of the fifth brood (third 

 crop) were appearing in considerable numbers in Central Alabama. 

 Moths bred from specimens of this brood which were sent to this de- 

 partment began to oviposit October 10, and October 15 larvae of the 

 sixth brood began to appear. It is probable that the sixth brood ap- 

 peared at an earlier date in Alabama, the development of the speci- 

 mens in my breeding-cages being retarded by the low temperature of 

 the room in which they were kept. 



One of the most remarkable things in the . natural history of this in- 

 sect is the power of flight which the moth possesses. There is no rea- 

 son to believe that the species can survive the winter north of the cotton 

 belt ; still, the moths have been repeatedly taken far north of the limit 

 of cotton culture ; we are, therefore, forced to conclude that these moths 

 have flown, aided perhaps by winds, from some portion of the cotton 

 belt to where they were found ; or that they are the descendents of such 

 moths. Dr. Packard has taken the moth on Coney Island and in Salem 

 Harbor. Mr. Edward Burgess states that it flew aboard his yacht in 

 Boston Bay, September 9, 1873. Mr. Grote informs me that it has oc- 

 cuiTed at Buffalo in September and October, and that he has heard of 

 it at Chicago, Detroit, London, Ont., Albany, and iSTew York. Profes- 

 sor Riley reports it from Chicago. The letter of Mr. P. R. Hoy, already 

 quoted, shows that it has occurred at Eaciue, Wis, in the autumn, 

 repeatedly, in great numbers. And one unbattered specimen was taken 

 at Ithaca, N. Y., in the fall of 1879. It will be noted that, in all the in- 

 stances in which the date of the occurrence of the moths in these north- 

 ern localities is given, they were found only in the autumn. This confirms 

 the conclusion that the moths cannot endure a northern winter, and 

 that their presence in the Northern States is dependent on migrations 

 from the South. 



That the moths found in the Korth may be, in some instances, simply 

 the descendants of moths that have migrated from the South, and that 

 this species has a l^orthern food-plant, is indicated by the fact that many 

 of the specimens taken were in a fresh condition when found. I was 

 led by this lact to endeavor to ascertain if the larva had ever been found 

 in the North. As Dr. Hoy informed me that he had repeatedly found 

 the moth while the wings were yet soft, not quite dry, I felt sure that the 

 larva could bo found near Racine if anywhere in the Northern States. 

 I therefore sent Dr. Hoy specimens to compare with the different larvae 

 18 Aa 



