18 THE REPORT OF THE No. 36 



per foot by the end of the season. But as there was little of this refuse on the 

 surface but a small proportion of the larvae were thus accounted for. Further, 

 in connection with this experiment in which the ploughing had been done October 

 12, and the count made November 20, the refuse in the eastern dead furrow was 

 found to have had its average population per foot of stalk and associated leaves 

 raised to but 1.33 larvae and that of the western dead furrow to 1.107 larvae, 

 both inexplicably small. This count is more to be wondered at in that practically 

 all larvae leaving the ploughed land must have passed through the refuse lying 

 in these dead furrows. It is estimated that on this ploughed strip 3,748 larvae 

 came to the surface. Did they migrate equally east and west there were suffi- 

 cient to raise the larval content of the refuse in the first 3.5 foot strip of unploughed 

 area by 3.3 larvae per foot. By actual count of a 12.29 foot section of this strip 

 the population was found to be but one larvae per foot on the eastern edge and 

 1.769 per foot on the western edge. A further study in the unploughed areas 

 between the experiments shows no clear indication of any general migration. 



Further studies will, of course, be made, using uninfested stalks in the inter- 

 vals between the ploughings. This was not done in these experiments owing 

 to the large number of larvae involved and their apparent tendency to enter 

 the first suitable hiding place encountered. 



The whole matter of the final resting place of the larvae is still in the realm 

 of conjecture and the work will have to be repeated, using uninfested cornstalks 

 to finally settle how serious is the danger of wholesale migration of the larvae 

 to wintering or pupating quarters from land ploughed in spring or fall. 



FURTHER NOTES ON THE LIFE HISTORY OF THE EUROPEAN 

 CORN BORER IN ONTARIO 



G. J. Spencer, O.A.C., Guelph 



The winter of 1921 had very little effect upon the larvae of the European 

 Corn Borer and only between 4 per cent, and 5 per cent, were killed by all causes. 

 However, this was more than in the winter of 1920, when a fraction less than 

 3 per cent, was killed. In addition to winter killing, the numbers of larvae in 

 some fields of corn stubble were reduced by woodpeckers which in one field were 

 found to have taken 60 per cent, of the larvae (H. G. Crawford's notes). The 

 Downey woodpecker is the chief bird concerned in this reduction during the 

 winter, although the Hairy woodpecker may be seen attacking cornstalks in 

 the fall. Birds are too uncertain an element to be depended upon to have any 

 material effect on the numbers of borers in the country. 



In spring, as soon as the weather warmed up, it was found that small greyish 

 red ants were taking many borers out of experimental cages. These ants were 

 kindly indentified by Dr. Wheeler of Harvard, as Lasius niger, Linn, var. ameri- 

 canus, the common garden ant, and we found that they stung any borers they 

 came across and dragged them down their holes. As high as 62 per cent, of borers 

 in their shelters of corrugated paper placed in covered tin cans, were found to 

 have been killed by these ants in a single night, and were being bitten to pieces 

 and hauled out of the can. In the field also, it was found that the ants entered 

 the tunnels in corn stalks and killed and removed the borers. However, when 

 the borers were completely covered up in their silken cases, the ants generally 

 left them alone, although it was found that even these were removed when all 

 the freely exposed larvae had been taken. In 1921 these same ants had been 



