100 REPORT UPON COTTON INSECTS. 



larvae of other broods, and those pupae which fall to the ground on ac- 

 count of the destruction of their leafy covering are soon destroyed by 

 ants. Even if they were not destroyed, they have no power of working 

 their way into the earth, as has been supposed by many. Of the very 

 many pupae which have been found in the ground and sent to this de- 

 partment by persons supposing them to be those of the cotton-worm, 

 not one has proved to be such. Many moths closely related to the cot- 

 ton-worm that is, belonging to the same family (the Noctuidae) pass 

 the winter in the ground in the pupa state. It is such pupae, and espe- 

 cially those of the boll-worm, that have been mistaken for those of the 

 cotton- worm. 



It has been contended by some that if the cotton- worm survived the 

 winter in the United States, it would exist in such numbers in the 

 spring that it would sweep away the young cotton plants at once. But, 

 from what we have seen of the disappearance of the " third crop " and 

 of the last brood, it is evident that in any case only a few individ- 

 uals survive the autumn. Numerous instances of pupae which were 

 undoubtedly those of the cotton-worm remaining alive after heavy 

 frosts, and even till midwinter, are on record ; but it is a suggestive 

 fact that there are but few well authenticated instances of pupae 

 producing moths after heavy frosts have occurred, those mentioned in 

 the letters of Professors Smith and Willet, quoted above, being the 

 only ones known to us. Is it not probable that observers have been 

 misled by the movements of pupae containing parasites ? Every ento- 

 mologist knows that dead pupae are frequently seen to roll about as if 

 alive, the motions being due to the parasite within. One of the most 

 interesting of the published observations on this point is the following, 

 by William Jones, in the Southern Cultivator, March 1, 1869 : 



Last fall we watched the caterpillar up to the time when their operations were 

 suspended by a severe frost. We found large numbers killed by the cold a few, in 

 sheltered spots still alive. Many were caught just beginning to wind up and prepar- 

 ing to pass into the chrysalid state, whilst the chrysalids were in every stage up to 

 the point of being ready to come out as moths. On the edge of tho field the chrysa- 

 lids were attached to briars and weeds, having wound themselves up in their leaves 

 (which winding up in leaves is, so far as we have observed, their invariable habit). 

 We collected a large number of these chrysalids, and, inclosing them in a bag, hung 

 them up in a porch facing northward. The thermometer indicated : 



November 2, 30. 



November 20, 28. 



November 22, 25. 



November 23, 24. 



December 2, 27. 



December 12, 12. 



December 13, 16. 



We examined them on the 14th of December, and found them still alive. On exam- 

 ining the bag again, about the last of December, to our very great disappointment, we 

 found that a bird had pierced the bag and eaten them. Wo shall have to wait, there- 

 fore, another opportunity to test the manner in which the insect passes through the 

 winter. About the middle of February we visited the aatno field again ; a majority of 



