June, '22 CRAWFORD & SPENCER: EUROPEAN CORN BORER CONTROL 231 



Although no direct evidence has been secured as to the origin of the 

 outbreak of the European corn borer, this may have been due in Elgin 

 and Middlesex counties to importations of broom corn from Europe. 

 From, correspondence, it has been learned that all Canadian broom 

 manufacturers prefer to use broom corn grown on this continent, but 

 in 1909-10 there was apparently a shortage of this product and one firm 

 at least located in this district, im_ported large quantities of corn from 

 Central Europe. 



President Arthur Gibson: The next paper is by Messrs. Crawford 

 and Spencer. 



THE EUROPEAN CORN BORER CONTROL MEASURES 



Joint results of studies in 1921, of H. G. Crawford, Dominion Department of Ento- 

 mology, Ottawa, Canada, and G. J. Spencer, Ontario Agricultural College, Guelph, 

 Canada. 



Complete control measures for the European Com Borer in Canada 

 have not as yet been perfected. Many facts have been worked out with 

 regard to its life history, enabling us to outline certain practices which 

 will go a long way towards keeping it in check in the districts where 

 it is most prevalent. The question of limiting it to these areas will be 

 discussed later. 



We know of no means of destroying the Etiropean Com Borer in the 

 pupal, moth or egg stages. But since it spends about ten months of the 

 year as a larva, it is in that stage that we can best bring about its destruc- 

 tion. 



At harvest time the borer is full grown and may be found in all parts 

 of the com stalk except the leaves, from the tassel down to the tap root. 

 Standing stubble or stubble plowed out and left on the surface with 

 debris of all sizes, and com stalks left in stooks or in standing sheaves 

 or lying on the grotmd, constitute ideal quarters for borers to winter 

 in, with remarkably low percentage of mortality. 



Control: falls imder two phases — 



Phase 1. The destruction of the borer in the stems and cobs of com. 



Phase 2. The destruction of the borer in the stubble and refuse 

 on the field after the crop has been removed. 



Phase i. The destruction of the borer in the stem. By cutting the com 

 as low and as early as is compatible with maturity, by far the largest 

 proportion of borers in a field can be removed in the stems. The longer 

 the stalks are left intact, the further down the borers will work and if 

 all are not mature but are still feeding, the more damage they do. The 



