30 BULLETIN 1103, U. S. DEPARTMENT OF AGRICULTURE. 



Pennsylvania, Ohio, and Michigan, the total infestation comprises 

 1,634 square miles in New York, 347 square miles in Pennsylvania. 

 757 square miles in Ohio, and 85 square miles in Michigan. The 

 commercial loss to the corn crop in the western New York area as 

 yet has been comparatively slight. The average infestation of field 

 corn here was slightly greater than in the preceding year. Of the 

 most heavily infested fields, 17 showed an average stalk infestation 

 of 32 per cent, and an average of two borers per infested stalk. 



Six fields of sweet corn representing maximum infestation in this 

 area showed an average of three borers per infested stalk, and a stalk 

 infestation averaging 33 per cent. Commercial damage throughout 

 the area, however, was very slight. 



With the exception of the newly infested area along the southern 

 shore of Lake Erie, the rate of natural spread previously observed, 

 i. e., about 6 miles per year, has not been exceeded in any of the prin- 

 cipal areas of infestation in the United States. It is suspected that 

 the slight uniform infestation along the shore of Lake Erie was. 

 caused by a forced migration of the moths across the lake from the 

 intense area of infestation prevailing in the neighborhood of St. 

 Thomas, Ontario. Records of the Weather Bureau observation sta- 

 tions on the southern shore of the lake show that for the first time in 

 five or six years the winds prevailing during the flight season of the 

 moths blew from north or northeast for several days at a time. 

 There is, of course, the possibility that this infestation may have 

 been caused by the drift of infested material from across the lake, 

 but as yet no traces of the presence of such material have been dis- 

 covered on the southern shore of Lake Erie, and, furthermore, the 

 uniform character of this mild infestation is believed to indicate some 

 other means of dissemination. In an attempt to solve this phase of 

 the problem the bureau has requested the permission of the Light- 

 house Service to station observers during the flight season of the 

 moths at several of the powerful lights maintained on the southern 

 shore in order to ascertain whether corn-borer moths are attracted 

 by these lights. 



During April, 1922, the Bureau of Entomology established a field 

 laboratory at Sandusky, Ohio, where a small corps of observers was 

 stationed for the purpose of observing the insect and its progress of 

 infestation. Additional plans for the combat of the insect include 

 the maintenance of the quarantines throughout the infested areas, 

 the scouting of all suspected territory, and the issuance of a new 

 Farmers' Bulletin giving the practical results of investigations car- 

 ried on by the bureau during the past three years. This will be fol- 

 lowed by a professional paper containing all important technical 

 details of the work. 



