312 



Journal of Agricultural Research voi. xxii, no. 6 



prefer loose mellow soil for egg-laying, it was thought that the condition 

 of the ground in summer-fallowed fields during the egg-laying period 

 might have considerable rafluence on the number of eggs deposited in 

 the field and on the percentage of loss the following spring. Since egg 

 laying does not begin until about August 15, fields which are not culti- 

 vated or disturbed in any way after July 1 5 become more or less crusted 

 and caked. Fields which are cultivated in any way during the last part 

 of July or during August, on the other hand, are very likely to be soft 

 and mellow during the egg-laying period, thus offering tlie very con- 

 ditions which the moths are seeking. Forty-eight fields, for which we 

 had data for both 19 19 and 1920, were therefore classified as crusted, if 

 they were worked only before July 15, or as mellow, if they had been 

 worked after that date. The percentage of loss for the variously worked 

 fields is shown in Table VII. 



Table VII. — Percentage of Porosagrotis orthogonia injury during IQIQ and IQ20 in 

 "crusted" and "mellow" sumtTier-f allowed fields. Data secured by personal interview 

 with grower 



Farmers were asked in questionnaires sent to farm bureau members 

 in counties infested with Porosagrotis orthogonia whether they had 

 noticed any relation between the condition of the soil in summer-fallowed 

 fields during August and the amount of pale western cutworm injury 

 the following spring. Sixty-eight grain growers answered this question. 

 Fifty-three said that injury was most severe in fields where the surface 

 soil was well pulverized, or, as one farmer stated it, "The more mulch 

 the more worms." Seven reported that the greatest injury had oc- 

 curred in fields that had been crusted during August, and five stated 

 that they could see no relation between soil conditions and cutworm 

 injury. 



The foregoing data, together with the fact that we have seen ovi- 

 positing females show a distinct preference for mellow fields, leads us to 

 the conclusion that the physical condition of the soil during the egg- 

 laying period has a very important bearing upon the amount of Poro- 

 sagrotis orthogonia injury that may occur the following spring. Accord- 

 ing to the data at hand greatest injury may be expected in fields in 

 which the surface soil is loose and well pulverized during the egg-laying 

 period. This loose, mellow condition may have been brought about in 

 summer-fallowed fields by tillage during late July and August or it may 



