REPORT OF THE EKTOMOLOGIST. 275 



The term " crop of worms " has become thoroughly incorporated in 

 the language of those most interested in the cotton-worm ; and, more- 

 over, it is a very convenient term. We shall therefore adopt it ; em- 

 ploying it, however, in the sense in which it is generally nsed. Thus, 

 by first croj) of worms we shall mean not the first brood, but the earliest 

 brood that is of suftlcient size to be easily noticed, and the second and 

 third crops are the two broods immediately following the first croi). 

 The term brood will be used in its usual sense. 



Disappearance of thikd crop. — While eoniemplating, in the 

 autumn of 1878, the immense number of worms which constitute 

 the third crop, I was struck with the fact that if even a thousandth 

 part of them v^'ere to mature and survive the winter the second brood in 

 the spring would be of sufilcient numbers to destroy all the cotton. I 

 was therefore interested in watching the disappearance of this so-called 

 third crop. 



The result of these observations shows that when the cotton-worms 

 occur in sufficiently great numbers to strip the cotton of its foliage the 

 gTeater part of that brood perishes at once. 



When the leaves of the cotton are destroyed the worms are forced to 

 migrate in search of more food, or, if they are fully grown, as is often 

 the case, in search of places in which to undergo their transformations. 

 While at Faimsdale, Marengo County, Alabama, August 28, 1878, 1 was 

 fortunate enough to witness an attempted migration of this kind, which 

 was attended with astonishing results. 



As soon as the larvae left the cotton stalks they experfenced great 

 difliculty in crawling over the surface of the ground. Clinging hold of 

 the loose i^articles of earth by its prolegs, a larva would attempt to 

 stretch its body forward in the manner peculiar to " loopers," but no 

 sooner was the anterior part of its body raised from the ground than 

 the insect, unable to balance itself upon the crumbling bits of earth, 

 would fall to one side with the full length of its body upon the ground. 

 Had it been a cloudy day, or had the ground been shaded, this would 

 not have been so serious a matter to the larva ; but, as is usually the 

 case at that season of the year, the sun was shining with an intense heat 

 and the surface of the sod was as hot as the sides of an oven. The 

 larvae did not seem to sufler so long as they were resting with their legs 

 upon the ground, but no sooner did one of them fall so as to touch the 

 earth with its body than it began to squirm violently. Sometimes a 

 larva would regain its position upon its legs, but the first attempt at 

 looping would result as before, and in a very short time, often not more 

 than one or two minutes, it would succumb. The number of worms de- 

 stroyed in this way is immense. I am certain that in the field in which 

 I made these observations there were to each square foot of land at 

 least an average of five dead worms that had been killed in the way de- 

 scribed within a few hours. Other causes tend to render this destruc- 

 tion more complete. Thousands of larvae are destroyed by ants. I\lany 

 pupae and lar^'ae which have " webbed up " and partially transformed 

 are deprived of their co^^ering of leaves by their voracious companions 

 and fall to tlie ground, where they perish. And still others, apparently 

 more fortunate in transforming within the folds of the leaves of other 

 plants than cotton, are imprisoned in their retreats by their companions 

 which follow and attempt to use the same leaves for the same purpose. 



Disappearance of the last erood. — Evidently after the disap- 

 pearance of the brood of worms known as the third crop, one or more 

 broods are usually developed in some parts of the cotton belt. Wherever 

 the earliest spring brood is of considerable size, there will be developed 



