THE ALFALFA CATERPILLAR. 31 



The damage in some alfalfa fields is quite often apparently cor- 

 related with the condition of the soil. A field seriously damaged 

 often reveals a poor soil — at least a soil not well adapted to alfalfa 

 culture, and consequently producing a slow-growing crop. Of course 

 not all of the fields damaged were of poor soil ; some of the very best 

 alfalfa fields were, seriously ravaged, but in these cases this was often 

 attributable to other factors. Sandy loams or light soils are the 

 best for alfalfa production, and consequently are the least damaged, 

 owing to the fact that the alfalfa, growing more rapidly, is often 

 able to recover from insect attacks and be ready for harvest before 

 any noticeable damage has been done. A heavy soil can be improved 

 and the growth of the alfalfa increased by deep plowing and thor- 

 ough preparation of the seed bed at time of seeding the crop and 

 then by renovating the alfalfa several times a year, either by disking 

 or by the use of an alfalfa renovator. By such a procedure in irri- 

 gated regions the soil will more readily take water, and thus plant 

 growth will be stimulated. 



A farmer who attempts to use up-to-date and proper cultural 

 methods is unfortunate indeed when his alfalfa fields, for which he 

 is caring properly, are just across the fence from fields that are run 

 down, and hence are breeders of insects. No matter how careful his 

 efforts, some damage may be done owing to reinfestation of his fields 

 from the butterflies supplied by his neighbor's field. Nevertheless 

 enough may be accomplished through his own efforts to pay many 

 times. 



Again, the amount of water applied is often insufficient, sometimes 

 because of neglect on the part of the rancher, and sometimes because 

 of scarcity of supply. The former case is under the rancher's con- 

 trol ; he should use care in applying the water and should eliminate 

 waste. Sufficient water should be used to provide for the prompt 

 development of the alfalfa crop, for in this way the farmer can 

 reap his crop earlier and before the caterpillars have effected much 

 damage. 



Soon after agents of the Bureau of Entomology began observations 

 and experiments looking toward the control of the species it was 

 noticed that damage to alfalfa was often, although not always, 

 associated with careless methods of farming and a lack of appre- 

 ciation on the part of some ranchers of the benefits to be derived 

 from careful, clean cultural methods. This is sometimes due to the 

 fact that the rancher is trying to cultivate more land than it is 

 possible for one man to farm successfully with the limited amount 

 of labor and capital at his disposal. A great many times poor man- 

 agement is responsible for a failure where other methods would have 

 meant success. 



