REMEDIAL AKD PREVENTIVE MEASURES. 139 



scarcely to be found, although the dead bugs were to be observed 

 almost as abundantly as were the living on the space untreated. 

 It must be remembered, however, that these experiments were 

 carried out in grass kept closely cropped by frequent use of the 

 lawn mower, and such areas can be sprayed much more effectively 

 than a wheat field, where the ground would have to be literally 

 soaked in order to reach all of the aphidids. 



In the light of these experiments field spraying seems an impracti- 

 cal measure, even when small areas are involved. Burning or plow- 

 ing would probably be more effective and the recommendations 

 would probably be more readily complied with, as the average farmer 

 does not usually have spray pumps of any description. 



Lime and sulphur was dusted on the plants in badly infested areas 

 with practically no benefits. 



CULTURAL METHODS. 



Examination of a large number of fields infested by Toxoptera, 

 extending over a wide range of country, resulted in securing a con- 

 siderable mass of information that may be included under the head of 

 cultural methods. 



The senior author visited Sumter, S. C, April 17, 1907, driving 

 over much of the country in that vicinity. All fields of fall-sown 

 oats, the only grain grown, were infested, there being no perceivable 

 difference in severity of attack between fields following cotton, 

 those following oats, and those on new ground, thus showing that 

 the pest had swept over the country, diffusing itself generally. 



At Winston-Salem, N. C, April 19-20, where both wheat and fall 

 oats were grown, the ravages of the pest were much more serious, 

 and fall-sown oats were completely ruined. A part of one field 

 that had been in oats the previous year had, that fall, thrown up a 

 heavy growth of volunteer grain, while the remaining portion was 

 free of this growth. Wheat was drilled directly across both these 

 areas on November 15, 1906, the whole field having first been pre- 

 pared by disking, leaving much of this volunteer grain undisturbed. 

 April 20, 1907, when examined by the senior author, the wheat on the 

 part that had been overgrown with volunteer oats the previous 

 fall was totally ruined, while on the clean part the damage was about 

 50 per cent. In wheat fields generally there was a marked difference 

 in severity of attack as between those seeded before and those sown 

 after about November 1, 1906, the later-sown suffering little while 

 that sown earlier, on ground where there was much volunteer wheat 

 or oats, was seriously damaged. This indicated that the trouble 

 had been aggravated by the volunteer growth at the time of wheat 

 seeding the previous autumn. It was very significant that in late- 

 sown fields on clean ground the injury was comparatively small. 



In Oklahoma it was observed by both the junior author and Mr. 

 C. N. Ainslie that late-sown and pastured fields were destroyed much 



