86 



disappearing as tliis became more abiiiidaiit and destructive. Fields of 

 young- corn and oats that bad germinated nicely and gave promise of a 

 bountiful crop were within the space of a few days swept out of exist- 

 ence, leaving the ground as devoid of growing grain as if none had 

 been planted. Even meadows did not escape, and in many places these 

 were left as bare and brown as in December. Of course tlie trouble was 

 confined to such lands as had been devoted to grass the preceding year 

 or on which the grass had not been subdued by the cultivation of the 

 previous crop, as, for illustration, a field of oats was nearly entirely 

 destroyed over an area that had produced wheat the previous season. 

 All sod lauds did not suffer alike, an occasional field escaping almost 

 entirel}^ On the Exx)eriment Station grounds one field had been 

 devoted to grass for two years and another for four, both being alike as 

 to soil and botli sloping to the northward. The first-mentioned field 

 was plowed in sirring and sown with oats, but nearly every plant 

 over the whole field was eaten oft' and killed by webworms. The second 

 field was jjartly spring-plowed and partly fall-plowed, but no percepti- 

 ble difference in point of attack was noted and the oats liere were not 

 destroyed. 



A field was broken in May, Imt the owner saw such numbers of the 

 worms that he became alarmed and delayed the planting of his corn for 

 two or three weeks. Some time after the field had been plowed I had 

 an opportunity to examine it, and found that the worms were leaving 

 the field, pushing outward along two sides and taking every blade of 

 grass as they went, leaving only the yarrow {AcMIlwa millefolium) that 

 grew among the grass. The attack was made among the dead and 

 decaying grass of last year, just above tlie surface of the ground. In 

 fields of corn or oats I noted that along the margins of the fields, where 

 the horses had traiiiped when turning, the injury was at first very 

 slight, though later on the worms reemed to sinead out over this and 

 devour the plants here also, Yery late fall or winter i^lowing appeared 

 ineffective, though there are some facts leading to the possibility of 

 early spring jjlowing being to a limited extent beneficial. Summer fal- 

 low was effective, though in one field where much injury was done the 

 worms were traced to small patches of grass growing about old stumx)s, 

 Of one thing this outbreak has convinced me, and that is that the farm- 

 ers of the Mississippi Valley at least must change their method of treat- 

 ing sod lauds — that is, lands that are broken up from meadow or i)asture 

 and planted. Just what to do I am at my wits' end to suggest, unless 

 it be to summer fallow. So far as I have been able to learn from lim- 

 ited collections made, the sx)ecies of Crambus most abundant between 

 May 29 and June 17 were Cramhus intermineUus and C. laqueatelliis^ 

 while C. mntahilis * was secured in more limited numbers. On May 20 

 C. intermineUus outnumbered C. lagueatellus in the proportion of 17 to 

 3, but on June 3 the latter outnumbered the former 11 to 2. Having 



* Determined by Professors Fernald and Smith. 



