278 EEPORT OP THE COMMISSIONER OF AGRICULTURE. 



larly toward the east and north. But this does not seem to be the case. 

 As we have already shown, in the spring of the present year (1879) the 

 worms were in Central Alabama a-s early as there was food for them. 

 And in 1873, when the first brood was so large as to attract general at- 

 tention, the worms appeared simultaneonsly (during May) in Jackson 

 County and Gadsden County, Florida; Decatur County, Georgia; Ma- 

 rion County, Mississippi; and Atascosa County and Victoria County, 

 Texas. 



Hibernation. — How does the cotton- worm pass the winter ? This is 

 a question most often asked respecting this insect, and it is only recently 

 that an answer could be given. 



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 croi>" and of the 

 last brood, it is evident that in any case only a few individuals survive 

 the autumn. Many have believed that the pupae of the last brood pass 

 the winter in the ground. This we now know cannot be the case, as the 

 larvae of the last brood web up in leaves in a similar way as do the 

 larvae of other brood Sj and those pupae which fall to the ground on 

 account 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 XoctukJae) — 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. 



The pupa of Alctia is rci>reseuted on Plate VII, fig. 10, and tliat of 

 the boll-worm on Plate VIII, fig. 9. But the most striking difixjrence 

 between the pupae of these two insects is exhibited by tlie form of the 

 spines at the posterior end of the body. In Aletia the spines are eight 

 in number, and are hooked as shov/n in the enlarged figure (Plate IX, 

 Fig. 2). The pupa of the boll-worm has but two spines, and these are 

 straight (Plate XVI, fig. C). By observing this point it is easy to dis- 

 tinguish the pupa of Alctia from that of the boll-worm ; and as soon as 

 this is generally known we will hear less frequently of the former being 

 plowed up. In fact there is now no reason for believing that the cotton- 

 worm ever enters the ground to undergo its transformations ; or that it 

 ever passes the winter in the pupa state. 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 suggest- 

 ive 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, referred to 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 pui)ae are frequently seen to roll about as if 

 alive, the motions being due to the parasite within ; and .--several in- 

 stances have come to our notice where pupae of Alctia, that were sup- 

 posed to be alive in midwinter, have proved to be parasitizeti. 



Many ])lanters believe that they have seen the adidt during winter and 

 early spring. But in nearly every instance when such moths have been 

 sent to an entomologist they have proved to belong to some other species 



