80 



by ants or other insects, but this does not seem probable. It seems 

 to be simply an inherent instinct. The bollworms appear to relish the 

 bodies of their unfortunate fellows, but soon sicken and die if com- 

 pelled to subsist for a lon^ time on this sort of food. Several were 

 experimented on in the laboratory b}^ feeding them on crushed cater- 

 pillars, but none so fed matured successfully. 



This is one of the most valuable factors in reducing the injury to 

 corn, for if all the larvae in an ear should feed peaceably together, as 

 is usual among many other species of caterpillars, they would no 

 doubt often consume it entirely. This would mean, in certain regions, 

 an almost complete destruction of the corn crop. During August, 

 1904, an actual count was made of a number of corn ears to ascertain 

 the number of larvae present. In 10 ears there were in all 168 larvae, 

 each containing from 8 to 38 in all stages of development, although 

 mostly quite small. This is an average of nearly 17 to an ear, or over 

 eight times the number which could eventualh^ mature. 



Cannibalism is not so important in lessening injury to cotton, since 

 the larvae are more isolated and do not meet one another so often. 

 During seasons of bad bollw^orm injury, however, it may be an appre- 

 ciable factor in their reduction. 



Aside from eating larvae and pupae of its own species, the larger 

 bollworms will often feed extensively upon the larvae and pupae of the 

 cotton caterpillar late in the fall when the latter is abundant, as well as 

 upon other species. 



LEAVING THE PLANT AND ENTERING THE GROUND FOR PUPATION. 



Bollworms feeding in ears of corn enter as very small larvae, as 

 alread}^ described, by eating down through the silks and between the 

 shucks at the tip of the ear. When they are complete!}^ grown no 

 opening for exit is present, and the larva must either eat its way out 

 in the direction it entered or bore directly through the shuck near the 

 tip. This last is the wa}' usually chosen, and after the larva has 

 emerged, a more or less sharply cut hole of the diameter of its bod}^ 

 is left through the shuck. Only a very few crawl but through the 

 silks, most probabl}^ because the latter are almost alwa3^s decayed and 

 moldy at this time. We were never so fortunate as to see a larva in 

 the very act of leaving the corn ear, which would suggest that this, 

 most probably occurs at some time during the night. Whether the 

 larva crawls down the stalk or drops directly from the ear to the 

 ground was not determined. Comstock (Kept. Cotton Ins. , 1879, p. 307) 

 believed that they drop directly from the ear. What evidence this 

 assertion is based upon is not given, and, to judge from the usual 

 cautious actions of the larva when crawling about, it would seem very 

 doubtful that they should do so. In a single instance, on August 4, 



