THE ALFALFA CATEEPILLAR. 35 



Salt River Valley there is a layer of subsurface water. This is lack- 

 ing in the Imperial Valley. Thus when a crop has been removed 

 in the former place alfalfa soon sprouts, and eggs are laid sooner and 

 have made some headway when irrigation has finally been accom- 

 plished. While there is a limit to the promptness with which a crop 

 can be removed from the ground after being cut, and consequently 

 a limit to the promptness with which the ground can be irrigated, yet 

 these measures should always be carried out just as soon as possible, 

 thus avoiding damage by reason of the difference noted. 



In 1912 Mr. Peter Aepli, living a mile south of Tempe, began cul- 

 tural methods especially meant to control outbreaks of the alfalfa 

 caterpillar. It is to be noted that even previous to this time Mr. 

 Aepli had carried on a system of crop culture that would secure the 

 maximum returns from his land; so that about the only change 

 in his methods was an addition of factors that take into consideration 

 the status of the alfalfa caterpillar at the time of each cutting; that 

 is to say, he cuts at a time that will do the most harm to any larvse 

 that may be present and before any damage is done to the alfalfa. 

 August 1, 1912, it was found that a considerable number of cater- 

 pillars were present in Mr. Aepli's field and that he would have to 

 cut earlier than he had intended in order to save it from serious 

 damage. On August 3 he cut the hay, doing a fine clean job. On 

 August 5 he removed the hay from the ground and then followed 

 this with disking and irrigation. The worms were all killed, the 

 present crop saved, and no further damage was done to the alfalfa 

 in that field that year. The effect of these careful and painstaking 

 methods was also noted in the field the year following. From Mr. T. 

 Scott Wilson's notes of August 4, 1913, is quoted the following: 



An 80-acre field of alfalfa across the fence from Mr. Aepli's is almost com- 

 pletely destroyed, while Mr. Aepli's is damaged but very little. Mr. Aepli is 

 cutting his hay to-day. The larvae are not full grown yet, so he is taking their 

 food from them before they mature. He usually cuts his hay close to the ground 

 and before it gets too ripe, hence Eurymus do not bother him much. 



Another example of the effect a careful system of clean cultural 

 methods will have upon caterpillar devastations is noted in a 640- 

 acre ranch just south of Tempe, Ariz. Here the clean-up methods are 

 accomplished by a combined system of haying and pasturing and are 

 quite successful. The ranch should really be termed a cattle ranch, 

 but after the owners' young steers that have been raised on their 

 range in northern Arizona are fed out in the winter and spring, sev- 

 eral crops of hay are made, stacked up in the field, and fed the next 

 winter. The hay from such crops is cut often, not allowed to get 

 overmatured, and as the owners employ a large force of men it is 

 hastily stacked and then, following this, 40 to 60 head of steers are 

 turned in for about three days, during which time they clean up 



