THE BOLL WORM CHARACTERS AND TRANSFORMATIONS. 3G7 
That those color varieties are not caused by a difference 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 larvffi are 
exposed and not hidden in feeding. 
As the worms grow they attack larger bolls, the young larva 1 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 ot the middle crop, the 
bottom crop being seldom seriously damaged by lleliothis. The half- 
grown worm finding a boll of a suitable age, begins at once to gnaw 
through the smooth covering, soon forming an opening 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 distinguished 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 Blight, rain penetrates through the 
opening, the boll soon rots and at tracts 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. li. 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 Holl 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 ot the Tennessee green -seeded 
cotton seemed to stop the spread of the disease. About 1850J 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 spot 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, perhaps, 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 
