THE EUROPEAN CORN BORER. 151 



few days these hatch. The young larvse begin feeding at once, and quickly 

 eat their way through the sheath before they tunnel in the main stalk. 

 On reaching maturity, which occurs the latter part of July, the larvjB 

 clear out a portion of the burrow, prepare an opening through which the 

 adults can escape, and after spinning a thin silken partition across the top 

 and bottom of this cleared space, transform to pupse. The moths emerge 

 for the second brood in about two weeks. This brood of larvoe becomes 

 full grown by late fall, but does not transform to pupae at once as in the 

 first brood. Instead, the winter is passed as larv'se within the stalks, 

 pupation taking place the following spring. 



Control. 



From the brief sketch of the life history it is apparent that there is no 

 hope of destroying this pest during the summer by the use of insecticides, 

 since all of its transformations take place within the plant. Our main 

 hope lies in the possibility of establishing a system of cultural methods 

 which wall enable us to prevent injury. The fact that the winter stage is 

 passed in the food plant suggests control measures which should result in 

 killing the great majority of the hibernating insects. These measures, if 

 carefully followed, should reduce the injury of the following season ma- 

 terially. 



1 . Burning the Stalks during the Fall or Winter. — While this is un- 

 doubtedly one of the most effective measures for the destruction of the 

 hibernating insects which can be adopted, it is somewhat wasteful, for the 

 stallcs are valuable either for feed or as a source of humus so necessary for 

 maintenance of fertility and texture in the garden soil. Burning, there- 

 fore, is inadvisable when other effective methods can be used. 



2. Burying the Stalks. — In home gardens the stalks may be put in 

 trenches and covered by at least 1 foot of soil. In larger market gardens 

 the stalks may be placed in the center of manure piles until decomposed. 

 In some cases plowing under might be resorted to, but the work must 

 be thorough or it will be ineffective. Any stalks left on the surface are 

 likely to harbor a crop of borers for the next season. If corn stalks are 

 distributed over the land and then cut up by running a disk harrow over 

 the field in both directions it should be possible to turn them practically 

 all under. 



It should be clearly understood that half-hearted work is of little value. 

 Occasional stalks which it may seem hardly worth the trouble to clean up 

 are likely to harbor enough borers to severely infest the spring crop. 



3. Feeding the Stalks. — From the economic point of view this is the 

 best possible means of destroying the hibernating insects, since the value 

 of the stalks for fodder is not materially affected by the presence of the 

 insects, and if properly carried out this method must result in the destruc- 

 tion of practically all of them. Feeding the stalks whole will be relatively 

 ineffective, since parts not eaten by the animals are likely to harbor in- 

 sects. Shredding the stalks, whether to be fed green or dry, must greatly 



