THE EUROPEAN CORN BORER AND ITS CONTROL. 17 



Injury to the Tassel. 



The newly hatched larva of the European corn borer first attacks the 

 unopened staminate buds of the tassel. After entering and feeding upon 

 the internal succulent parts of several staminate buds, it enters the 

 stalk 2 or 3 inches above the lower branches of the tassel, and tunnels 

 upward for 2 or 3 inches. It then returns to its original entrance and 

 tunnels toward the base of the plant. 



Within a few days the larva completely consumes the central pith of 

 the tassel stalk, soon causing a break at the point where it originally 

 entered. The broken-over portion of the tassel still remains partly 

 attached to the plant, and in this condition its yellow-white color and 

 broken-over position make it a very conspicuous object in a field of corn 

 in contrast to the green color and upright position of tassels not infested. 



This t^-pe of injury indirectly affects the formation of corn kernels on 

 the cob by' greatly reducing the amount of pollen. In the process of 

 fertilization, pollen from the tassel must fertilize the corn silk in order 

 that kernels may develop. It is apparent that if pollen is not present 

 in large enough quantities the resulting ear of corn will show a lack of 

 fully developed kernels. Field counts made in badly infested areas 

 showed that as high as 61 per cent of the corn tassels had been broken 

 over and were barren of pollen. This high percentage of injury was more 

 common on late corn than on early corn, due, perhaps, to the greater 

 number of larva? present. Out of a total of 3,810 tassels, counted in a 

 field of late season, sweet corn at West Medford, Mass., 2,344 tassels, 

 or 61 per cent, were infested and broken over. Many ears of corn from 

 this field were noticeably small in size and with few kernels, even though 

 not themselves directly injured by the insect. Much of this loss is 

 beUeved to have been caused by the injury to the tassel, although this 

 belief is contrary to the opinion of botanists consulted. It is apparent 

 that botanists must reverse their opinion in this matter. 



Injury to the Stalk. 



In nearly all cases the terminal internode, bearing the tassel, furnishes 

 sufficient food for the full development of a single larva. Other larvse, if 

 present in the same tassel, are forced to leave and tunnel in the lower 

 parts of the plant for food. Their operations are generally confined to 

 the upper two-thirds of the stalk, but, if numerous, they may extend 

 their tunneling to the very base of the stalk, or even into the upper part 

 of the taproot. Wlien several larvse are feeding in the same stalk the 

 pith is nearly, if not entirely, consumed, and the interior of such a stalk 

 is found to be practically hollow. There is a tendency for the larvae to 

 work in the internodes of the stalk, but, when necessary, they commonly 

 pierce, and feed upon, the nodes. This latter observation is contrary 

 to published records on the habits of the species by European writers. 



A total of 75 corn plants, growing in a badly infested field at West 



