14 MASS. EXPERIMENT STATION BULLETIN 189. 



any plant possessing a moderately soft, fleshy stem or stalk, or bearing 

 a soft seed head during its early growth. Along the outer edge of the 

 infested region, and in areas only recently invaded, the insect is aknost 

 always found exclusively in corn. 



In badly infested fields the corn plants are frequently inhabited by so 

 many feeding larvse thai all of the desirable plant tissue is quickly con- 

 sumed, and under these circumstances the larvse must leave their original 

 host and enter other food plants growing in the vicinity in order to obtain 

 food. Many of the eggs and smaller larvse are sometimes dislodged 

 from their original location on the corn plant and fall to the ground or 

 upon other species of plants growing underneath, or between the rows 

 of the corn, to subsequently infest these other plants. This character- 

 istic often accounts for the great variety of infested plants found in the 

 vicinity of badly infested corn fields. 



The early season corn plants become dry and hard during July and 

 August. Many of these plants contain belated P. nvbilalis larvae of the 

 first generation, as well as small larvse of the second. The comparatively 

 soft tissue of late season plants growing in the vicinity often attracts the 

 corn borer larvse from their original food plant. 



Plants other than corn, growing in areas planted to corn during the 

 preceding year, frequently have eggs laid upon them by moths resulting 

 from the over win cering larvse in the crop remnants of the preceding year. 

 In other instances the moths drift into areas where corn plants are absent, 

 and deposit their eggs upon the most attractive food plant at hand. It 

 is believed, however, that the moths prefer to deposit their eggs upon 

 corn. 



Another factor which is of interest in connection with selection of food 

 plants is that the larvse prefer large healthy plants, growing in well- 

 fertilized land, to small plants of the same species, growing under less 

 favorable conditions. 



List of Food Plants. 



The following table will show the list of food plants in which the Euro- 

 pean corn borer has been found in Massachusetts to date. This list has 

 been compiled by dissecting the larva from each plant mentioned. Adults 

 were reared in instances where the identity of the larva was in doubt. 



The plants are arranged in order, with regard to their preference as 

 food plants by the insect. 



