32 BULLETIN 124, 17. S. DEPARTMENT OF AGRICULTURE. 



CLOSE CUTTING AND CLEAN CUTTING. 



In harvesting the hay crop ranchers usually have to depend upon 

 labor that, while often the best obtainable, is not by any means of 

 the best class, and thus cutting is often done in a careless manner, 

 stubble is left high and ragged, bunches of hay are left uncut at turn- 

 ing rows or on borders, ditch banks and fence rows are rarely or 

 never cut, and the field presents the spectacle shown in Plate I, fig- 

 ure 3, page 4, and Plate II, figure 3. Thus any caterpillars that may 

 still be present have a considerable amount of alfalfa upon which to 

 feed and develop, and soon do so, so that the butterflies from these are 

 ready for the next crop. Such places also afford bloom which attracts 

 adult butterflies from other fields, and these lay eggs on the new 

 alfalfa that soon springs up. If such neglected fields are treated as 

 are those shown in Plate II, figures 1 and 2, there will be no food to 

 enable any remaining caterpillars to complete their development ; 

 besides this, there will be no protection for them from an early 

 irrigation or the rays of the hot sun, either one of which will kill 

 them. Heat of the midday sun, accompanied by prompt irrigation 

 immediately following such clean cutting, will nearly always kill 

 Eurymus larvse, especially in the warm Southwest. This is such an 

 important item that one should not hesitate to go to the necessary 

 expense in order to secure such a condition of cleanliness. In two 

 cases in the Imperial Valley in 1910 it became necessary, because 

 the hay had lodged badly, to remow a field at a cost of from 30 to 

 50 cents per acre, and in each case the results obtained in the follow^ 

 ing crop more than paid for the cost of the experiment. 



EXPERIMENTS AND OBSERVATIONS IN CALIFORNIA. 



In California, in 1910, 10 fields were selected in which good cul- 

 tural conditions were to be created and in which methods were to 

 be inaugurated that would not further the development of the cater- 

 pillars. The thing done in these fields was to put them under a sys- 

 tem that would remedy as far as possible all or part of the defects 

 recorded on a pre/vious page. Driring that season (1910) a large 

 part of the damage was due to the caterpillars of the third and 

 fourth generations, the first and second not being numerous enough 

 to assume any serious aspect. The task, then, was to keep their 

 numbers below the point at which they could do any considerable 

 damage. The time to start this control work was naturally with 

 the earlier generations. The 10 fields mentioned (no two of which 

 had had the same conditions of culture previous to that year, and 

 which had all suffered more or less damage the year before, namely, 

 in 1909) were given what might be termed clean culture, or careful 

 management. Just as soon as possible after removing a crop of hay 



