February, ’24] 
parks: corn borer clean-up 
141 
some quantity of the larvae producing moths upon the old corn land 
occupied by a crop. However, under general field conditions, as was 
the case in the field under study where as high as 33,800 per acre were 
present in the spring, practically no larvae were present in the soil to 
produce moths and there is apparently little danger under field condition 
where clean ploughing is practised of sufficient moths emerging from 
the field to maintain an infestation of any importance in Southwestern 
Ontario. 
The factors which brought about the reduction in numbers of the 
larvae and their relative importance have not as yet been adequately 
evaluated and careful investigation of this part of the problem is in 
progress. It is doubtless associated with the prolonged exposure, 
particularly in the spring, to the attacks of ants (Lasius niger var. 
americana) beetles and birds, together with the dryness and high tem¬ 
peratures of the surface soil. 
Based upon the findings arising out of these investigations we are 
unhesitatingly recommending in Ontario the clean ploughing of the com 
stubble as the most practical and effective method as yet known for the 
disposal of that part of the corn borer population which is left in the 
field after harvesting and this practice with the destmction of the com 
refuse about the barn yard and feeding paddocks, is considered the most 
important operation for the control of this pest. 
q917. Vinal, S. C. The European Corn Borer, Bull. 178, Mass. Agric. Exp. 
Station, p. 151. 
2 1919. Vinal, S. C. and Caffrey, D. J. The European Corn Borer and its Con¬ 
trol. Bull. 189, Mass. Agric. Exp. Station, pp. 60-61. 
3 1921. Felt, E. P. European Con Borer, Bull. 247-248, N. Y. State Mus. Rep., 
N. Y. State Ent., XXXV, p. 25. 
4 1922. Caffrey, D. J. and Worthley, L. H. The European Corn Borer and its 
Control, Farm Bull. 1294, U. S. Dept. Agric., pp. 37-38. 
5 1922. Crawford, H. G. and Spencer, G. J. The European Corn Borer, Control 
Measures., Jour. Econ. Ent., XV, 231-236. 
6 1923. Spencer, G. J. and Crawford, FI. G. The European Corn Borer in On¬ 
tario. Bull. 295, Ont. Agric. College, p. 10. 
7 1923. Crawford, H. G. Ploughing as a Factor in the Control of the European 
Corn Borer in Ontario, Ann. Rep. Ont. Ent. Soc., XXXV, p. 13-18. 
THE EUROPEAN CORN BORER, CLEAN-UP METHODS 
By T. H. Parks, Ohio State University 
Abstract 
Conditions under which corn is grown in northern Ohio make clean-up work for 
European corn borer, Pyrausta nubilalis Hubn., difficult to carry out. In much of 
the infested area the corn is cut by hand and much of the stalk is left in the stubble. 
Machine cutting is being advocated to remove from the field more of the stalks, 
