June, 22 mclaine: spread European corn borer 227 



THE SPREAD OF EUROPEAN CORN BORER IN SOUTHERN 



ONTARIO 



By L. S. McLaine, Ottawa, Can. 



When the European Com Borer was reahzed to be a serious pest, 

 that is, in the summer of 1918, the Canada Department of Agriculture 

 took steps to warn the general public of the danger of introducing this 

 pest into Canada, and also carried on investigations to determine the 

 amount of corn and other products likely to harbour the borer that 

 had been imported into the Dominion from the infested districts in 

 Massachusetts. As a result of these investigations scouting for the 

 pest in the maritime provinces was carried on during the summer of 

 1919. 



With the discovery of the insect in western New York in the fall of 

 that year, the attention of the Department was directed to the possi- 

 bility of the pest having spread into the province of Ontario. Some 

 scouting was done in Welland county and along the Niagara River 

 that fall, but was soon discontinued on account of the lateness of the 

 season and the imfavotu-able climatic conditions. Plans were made, 

 however, to restmie the scouting in this territory the following summer. 



On August 10th, 1920. the first infestation was found near Lorraine 

 Station, Humberstone township, Welland county, Ont. The larvae 

 were small in size and were collected in a field of ensilage corn. A 

 preliminary survey of the infestation showed that it was exceedingly 

 light, but widely scattered. On August 22d, a farmer living near 

 St. Thomas, Ontario, submitted some samples of larvae found in his 

 field com and which were readily identified as caterpillars of the Euro- 

 pean Corn Borer. A prompt examination of this district showed the 

 degree of infestation to be much greater than that in Welland county. 



With the co-operation of the Ontario Department of Agriculture 

 extensive scouting was started at once. The extent of the infestations 

 exceeded by far anything that had been anticipated and as the season 

 was advancing rapidly, the scouting had to be carried on at undue speed. 



At the close of the scouting work it was found that there were two 

 distinct infestations in southern Ontario, the first centering about 

 Welland county, and the second centering about Middlesex and Elgin 

 counties. During the scouting season one hundred and five townships 

 in thirteen counties were examined, thirty -five of which were found 

 infested by this insect. The area found infested covered approximately 

 2,780 square miles. 



