THE BOLL WORM CHARACTERS AND TRANSFORMATIONS. 367 



That these color varieties are not caused by a diflereuce in food is 

 shown by the fact that all the variations occur in specimens feeding on 

 one and the same plant. Those feeding on maturing corn are always 

 dark, however, and the colors brighten in proportion as the larvae are 

 exposed and not hidden in feeding. 



As the worms grow they attack larger bolls, the young larvae hav- 

 ing mainly confined themselves to the buds and newly -formed bolls. 

 (Plate IV, Fig. G.) The worms may, therefore, be said to progress down- 

 ward, the younger individuals being found mainly upon the top crop, 

 while the older larvae bore into the older bolls ol the middle crop, the 

 bottom crop being seldom seriously damaged by Ilcliothis. The half- 

 grown worm finding a boll of a. suitable age, begins at once to gnaw 

 through the smooth covering, soon forming an oj)ening as large as 

 the diameter of its body, and through this opening it gradually works 

 its way into the interior of the boll. Frequently the spot first tried 

 proves too hard or otherwise distasteful, and the worm leaves it either 

 for another boll or for another spot on the same boll. Infested bolls 

 can usually be distingui^hed by the opening, but occasionally this is 

 hidden by the involucre. Having devoured or partially devoured the 

 contents of one boll, the worm leaves it for another. Even if, however, 

 the damage to the contents has been slight, rain penetrates through the 

 opening, the boll soon rots and attracts other insects (principally Dip- 

 terous and Coleopterous), which finish the work of destruction. In this 

 way an immense amount of damage can be done by a single larva. 

 Prof. E. W. Jones says in his report : ^' The amount of damage done by 

 a single worm is surprising. I have counted eighteen young bolls 

 shriveling, decaying or fallen, besides many blooms and unopened flower 

 buds pierced; all the work of one Boll Worm, and that not grown." 



The disease known as '• boll-rot " has recently been laid to the account 

 of the Boll Worm. This disease is said to have made its appearance as 

 early as 1810, and to have prevailed for ten years or more, frequently 

 destroying whole crops. The introduction of the Tennessee green-seeded 

 cotton seemed to sto}) the spread of the disease. About 1850, however, 

 it is said to have reappeared, and since then has been an occasional 

 source of considerable damage to the crop. The rot manifests itself at 

 first by a slight discoloration, resembling a small sjjot of grease. Either 

 one or all of the interior divisions soon rots, and the boll frequently 

 bursts and discharges a putrid mass. The disease has been variously 

 attributed to the agency of some fungus growth, to an organic disease 

 of the plant brought on, i:)erhaps, by a superabundant moisture of the 

 soil, and to the attacks of insects. The results of the rot — in the shape 

 of insects attracted by the diseased condition of the boll — have long 

 been considered as among the causes. 



Professor Stelle, in one of his reports to us (see Appendix III) be- 

 lieves that the rot can all be laid at the door of the Boll Worm. He 

 claims by his observations to have proven that the greasy-looking 



