KEW YORK STATE MUSEUM 23 



The above figures should be compared with the 50 per cent ear 

 infestation in Canadian field corn, 1920, having a 70 per cent to 

 90 per cent stalk infestation and the practical destruction of early 

 planted sweet corn in the badly infested Canadian area last season, 

 this latter indicating a very general, presumably 100 per cent ear 

 infestation in the worst affected fields. 



Conditions affecting infestation. The development of the corn, 

 the nearness of infested material, the direction of the prevailing 

 winds and the stubble infestation all appear to have a material 

 influence upon the amount of infestation. 



The influence of the time of planting in the infested area was 

 strikingly shown by two fields of howling mob sweet corn, one 

 planted May 20th and next an infested field of last year, and the 

 other planted July 7th and only 100 feet away across the road. 

 The first had a stalk infestation of 10.52 per cent but in the second 

 only one afl^ected stalk was found. Furthermore, 3' acres were 

 planted with early dawn and golden bantam May 8th and 13th and 

 they had a stalk infestation of 4 per cent while a nearby acre of 

 golden bantam planted June 25th had but three stalks affected, or 

 less than i per cent. 



Messrs Crawford and Spencer, discussing conditions in the badly 

 infested Canadian area in 1921, state that in general corn sown 

 before May 24th was either practically ruined or suffered severe 

 loss; that sown between May 24th and June ist was hea\aly 

 infested but suffered relatively less or but slight, actual loss depend- 

 ing upon the type of corn; while the corn sown after June ist, 

 although in some cases showing a fairly high percentage of infesta- 

 tion, carried few larvae and suffered practically no loss except in 

 the case of sweet com. 



It should be borne in mind in this connection that the date of 

 planting is only an approximate indication of the condition of the 

 corn at the time the moths fly. A rather striking illustration of 

 this was found 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 sweet corn. 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 18.18 per cent 

 of the white dent. The owner stated that the evergreen developed 

 somewhat slower and the probabilities are that the white dent was 

 in a more attractive condition at the time the moths were flying and 



