MR. GROTE'S PAPER. 117 



after the cultivation of the cotton plant was introduced into the Southern States, the 

 cotton- worm never appeared. The date at which it first appeared in central Alabama 

 has been differently stated to me, but it evidently but little preceded the late war. 

 That the moth is capable of sustaining long and extended flight is readily proven. 

 Professor Packard observed the moth off the coast of the Eastern States, as also Mr. 

 Burgess. I have observed the moth in October in Buffalo, N. Y., as also Dr. Harvey. 

 According to Mr. Riley the moth has been observed in Chicago, I presume in the fall. 

 It seems that the moth follows the coast-line northward, as also the water-courses 

 that empty into the Gulf of Mexico. It is noteworthy here that the water-shed of the 

 Ohio and Mississippi extends to within fifty miles of Buffalo. As an example of the 

 prolonged flight of moths, I will state that I have observed in the Gulf Stream, off 

 the Carolinas, and out of sight of land, in the month of August, large numbers of a 

 moth, the Agrotis annexa of Treitschke. 



Again, I have been struck by the absence of parasitic checks to the cotton-worm 

 in the South. I could never discover any, although such may exist. Spreading, as I 

 "believe it to do, as a moth, the absence of peculiar parasites to the worm may be 

 reasonably accounted for. I have already and elsewhere pointed out, that in order to 

 make the first brood of the cotton- worm the progeny of the so-called "hibernating" 

 individuals (as Professor Riley would suppose), a period of several months had to be ac- 

 counted for, since these "hibernating" moths could not wait till midsummer to de- 

 posit their eggs ; and while the cotton is young, and even before it is up, iusect life 

 is active, and the weather is warm and other vegetation fully out in the region of 

 the South where I have lived. There is also no reason to believe that the cotton- 

 worm ever breeds in the North, and this, notwithstanding Professor Riley's sugges- 

 tions to the contrary in the sixth report before mentioned. The worm uever has been 

 noticed on any other plant than the cotton, and in the South perishes by- thousands 

 rather than eat any other. The habit of wandering in masses when food fails is a 

 proof of this, as while the worm is supplied with cotton-leaf it never quits the plant, 

 transforming to the chrysalis on the stalk which has furnished it nutriment. The 

 wandering habit is not normal, but accidental, and the worm is not "gregarious" 

 like the " tent caterpillar." Its " hibernation" with us must also be regarded as acci- 

 dental, or at least as barren of results. For when springs comes the Aletia argillacea 

 has vanished, and is not found with the hibernating species of Lepidoptera renewedly 

 active. And if it were found in February and March, it would find no cotton plants 

 upon which to deposit its eggs. If oviposition ever takes place in these months in 

 the cotton belt, the young cotton, free from worms, disproves its efficacy. 



It is possible that in the southern portions of Texas, or the Floridian peninsula, the 

 Aletia may sustain itself during the entire year ; I have no means of information on 

 this point. My observations are made on its occurrence over the central and principal 

 portions of the cotton belt, and into which I believe it to be imported de novo every 

 season that it there occurs and from more southern regions. I conclude, therefore, 

 that while the cotton plant is not indigenousfto the Southern States (where it becomes 

 an annual), the cotton-worm moth may be considered not a denizen, but a visitant, 

 brought by various causes to breed in a strange region, and that it naturally dies out 

 with us in the cotton belt, unable to suit itself as yet to the altered economy of its food- 

 plant and to contend with the changes of our seasons. When this fact is comprehended 

 it will simplify the process of artificial extermination by limiting the period during 

 which we can successfully attack the cotton-worm, and by doing away with a certain 

 class of proposed remedies. From the foregoing it will be evident that, 1, the arti- 

 ficial agent employed to destroy the cotton-worm must be employed against the first 

 brood as it appears in any given locality during the progression of the moth north- 

 ward ; and, 2, that in order to be effectual, a concerted action in the application of 

 the remedial agent in any given locality will be found necessary. 



Before entering upon any discussion of the theory of migration let us 

 examine the data upon which the theorists have based their conclusions. 



