February, '21] felt: eiropean corx borer 87 



side of the more heavily infested section mentioned above, and extends 

 up the river for about eight miles and back from the river some five miles. 



The above statements regarding infestation should not be construed 

 as implying that all fields in either area are necessarily infested to the 

 degree indicated because as will be pointed out below, much appears to 

 depend upon the time of planting, the nearness of infested materials 

 and the direction of the prevailing winds. 



The influence of the time of planting in the infested area is strikingly 

 shown by two fields of Howling Mob sweet com, one planted May 20th 

 and next an infested field of last year and the other planted July 7th 

 and only 100 feet awa}' across a road. The first had a stalk infestation 

 of 10.52 per cent and m the second onl}- one affected stalk was found. 

 In another instance over three acres w^ere planted with Early Dawn 

 and Golden Bantam May Sth and 13th and had a stalk infestation of 

 four per cent, while a nearby acre of Golden Bantam planted June 25th 

 had but three stalks affected or less than one per cent. 



The date of planting is only an approximate indication of the condi- 

 tion of growth at the time the moths Hy. A rather striking instance of 

 this was fomid in western New York in a large field which was planted 

 on the same date, approximately one-half being in White Dent and the 

 other half in Evergreen. The latter was nearer the presumable source 

 of infestation and yet showed a hill infestation of but 7.5 per cent, as 

 compared with the White Dent of 18.18 per cent. The owner stated 

 that the Evergreen developed inore slowly and the probabilities are that 

 the White Dent was in a more attractive condition at the time the moths 

 were flying and consequently they passed over the Evergreen in great 

 measure and oviposited mostly in the White Dent. It is worthy of 

 note, in this connection, that depressions in rolling fields, if conditions 

 permit early and vigorous growth, are likely to show a heavier infesta- 

 tion. 



The nearness of infested material has a decided influence upon infesta- 

 tion. The heaviest infested fields were near known sources of infesta- 

 tion and in a number of cases the infestation began and was decidedly 

 more marked on the side of the field next an earlier infested area or 

 source of infestation. 



The direction of the prevailing winds likewise has an important 

 influence. One of the most striking cases was that of two fields in the 

 Mohawk river bottom, one with a stalk infestation of 19.94 per cent, and 

 the other of only 5.46 per cent. The first was in direct line of the pre- 

 vailing winds from an infested area of the preceding season and the other 

 only about 200 feet north and therefore outside the presumably usual 

 drift of the moths. 



