THE EUROPEAN CORN BORER AND ITS CONTROL. 11 



diately west and north of the city of Boston, Mass., and has as its limits 

 the towns of Beverly, Danvers, Topsfield, Peabody, North Reading, 

 Reading, Woburn, Lexington, Waltham, Newton, Brookline and Boston. 

 (See map.) All the towns within these limits are infested to a greater 

 or less degree. 



Granting that the section near the mouth of the Mystic River was the 

 original point of entrance, it will be noted that the European corn borer 

 has shown a decided tendency to spread in a northerly and northeasterly 

 direction. This characteristic has been exhibited by other insects intro- 

 duced from Europe, notably the gj'psy moth {Porthetria dispar L.) and the 

 brown-tail moth {Euprodis chrysorrhoea L.). An examination of the 

 meteorological records shows that during the periods when the adults of 

 P. 7nibilalis are in flight, the prevailing winds are from the south and 

 southwest. This may be the decisive factor in influencing the direction 

 of the spread of P. nubilalis, as it is thought to be in the case of the other 

 insects mentioned. 



The area given above is believed to represent very accurately the 

 limits of the district as 3'^et invaded by the European corn borer. During 

 the past season several men were engaged in determining these limits. 

 In addition to this, the surrounding and contiguous territory in the States 

 of Massachusetts, New Hampshire and Maine was examined for possible 

 isolated infestations. Some other sections of these States were also ex- 

 amined because of the fact that their trade with infested sections near 

 Boston might have led to the involuntary introduction of the pest in 

 infested plant products. This was especially true of the sumaner hotel 

 districts in Maine and New Hampshire, to which shipments of sweet 

 corn were frequently made that had originated in the badly infested 

 market-garden districts near Boston. 



Territory examined in Massachusetts. 



All of northeastern Massachusetts was examined to the New Hamp- 

 shire line, and as far west 3S Tyngsborough, Westford, Acton, Sudbury, 

 Wayland and Natick. On the south and east the territory was examined 

 lo Dover, Westwood, Canton, Randolph, Holbrook and Wejonouth. 

 Special attention was given the sections adjacent to the large cordage 

 factories located at Andover and at Plymouth, with the idea that the 

 pest may have been imported with hemp consigned to these factories. 

 No infestation was found, however, outside the limits of the area pre- 

 viously designated. 



Several reports were received during the season that the European 

 corn borer was present in wadeh' separated localities throughout the 

 State. Care was taken to investigate all of these reports, but 9side from 

 those originating within the known area of infestation, it was found that 

 insects other than P. nubilalis were responsible for the reported injury. 



