THE QUESTION OF HIBERNATION. 21 



South, and that the first crop raised thereafter T^as infested. Professor 

 Comstocktook particular pains to make inquiries on this head, and found 

 that some patches of cotton had been grown every year in such sections. 



In favor of hibernation in the southern portion of the cotton belt may 

 be urged [1] the appearance of the moth on the wing during mild winter 

 weather, and its being found torpid in sheltered situations, as is insisted 

 on by so many ; [2] the first appearance of the worms in very small 

 numbers, and in the spring of the year, as attested by recent observa- 

 tions; [3] their reappearance each year in the same spots, not on the 

 sea-coast nearest to the tropical zone, where we should expect them on 

 the theory of annual incoming, but at various points far inlind ; [4] the 

 coming of the moths in large numbers and as immigrants into the 

 northern portions of the belt, being always preceded by the appearance 

 of the worms and their gradual increase at some other, generally more 

 southern or western, points; and [5] the decrease of cotton culture in 

 Central America and the West Indies, as appears from market statis- 

 tics, and the absolute absence of the worm in the Bahamas since 1866, 

 as ascertained by Mr. Schwarz while there in the spring of 1879. 



The strongest fact against hibernation was, perhaps, the period elaps- 

 ing between the disappearance of the moths in March and the first 

 appearance of the worms, or, to put it in another form, the absence of 

 the worms on the young and tender cotton. The period during which 

 the species was not observed is already reduced by the facts given in this 

 report to less than one month instead of three, and this is much less than 

 the time elapsing between the issuing from winter quarters of other 

 well-known Lepidoptera that hibernate in the imago state, and the first 

 appearance of their larvae, numerous illustrations of which fact might 

 be cited.* 



On the whole, therefore, the weight of evidence is strongly against 

 the theory of annual extermination, in the southern part of the belt, and 

 the fact of the hibernation of Aletia there may be said to rest on as 

 good evidence as that of many other species in which it is admitted 

 without question. Yet Aletia is beyond doubt killed out each winter in 

 the northern portion of the cotton belt, and all the arguments in favor 

 of annual extinction and incoming de novo have force when restricted 

 to this section. Just where the separating line lies between extinction 

 and survival is not so easy to decide, and for the present we can only 

 refer to that given in the Introduction as the result of the investigation 

 so far as it has gone. This conclusion that the moth does and can hiber- 

 nate in the United States does not preclude its occasional incoming from 

 foreign, more tropical countries, or the possibility of its being brought 

 by favorable winds from such exterior regions, just as originally must 

 have been the case when the species was first introduced. The facts 

 indicate, however, that this kind of immigration is less frequent now-a- 

 days than it was in the beginning of the century. 



* The interYening period is atlll farther lessened, as will be seen from the remarks on page 12 and in 

 Note 12. 



<y^^ 



