THE ALFALFA CATEEPILLAR. 39 



be laid upon the first, consisting of longer brush, with the butts trimmed a 

 little further back so that you will have in effect two brush harrows, one 

 following the other. Another plank should then be laid on the brush butts 

 and bolted to the under plank. In weighting this drag, lay an ordinary tooth 

 harrow, with the teeth down, directly on the brush drag. This makes a very 

 even weight, at the same time it is so flexible that the drag will work its way 

 down into the small depressions as well as over the larger elevations of the 

 fields. 



A larva exposed to dust and hot sun soon dies. On September 4 

 three larvae were placed in a dusty spot by Mr. Wilson, and within 

 a few minutes all were dead. The next day the experiment was 

 repeated, and all larvae died. In all about 50 larvae were exposed to 

 the dust and sun, and of this number only 1 was able to crawl back 

 to alfalfa, the rest dying before they had crawled 10 inches on the 

 dust and dry dirt. The sun was very hot, and the temperature, 4 

 feet from the ground, was 97° F. These experiments show why so 

 many larvae die following careful methods of haying. They have 

 no protection from the hot sun when such methods are carried on. 



CONCLUSIONS REGARDING CONTROL. 



Keep the ranch in the best possible cultural condition. Irrigate 

 it often and thoroughly and as soon after cutting as the crop of hay 

 can be removed from the ground. 



Renovate every winter and during the month of August, or even 

 oftener if possible, either by disking or by the use of an alfalfa ren- 

 ovator, thus disturbing any pupae that may be present, and putting 

 the land and alfalfa in condition for good growth of succeeding 

 crops. 



Cut the alfalfa close to the ground and clean, especially along the 

 ditch banks, borders, and turning rows, as well as in the main part 

 of the field. 



Cut the alfalfa earlier than is the general rule. The proper time 

 is when it is just coming in bloom or is one-tenth in bloom. Watch 

 for caterpillars in the early spring crop, and if many are observed 

 about grown, cut the hay a few days before it is in bloom, and thus 

 save the next and future crops. 



A minimum amount of damage occurs in fields that are systemati- 

 cally pastured all or a part of the time. 



A field should never be abandoned because the caterpillars threaten 

 the destruction of a crop of alfalfa before the hay can possibly ma- 

 ture. Mow it at once^ cutting it low and clean, thus saving part 

 of the present crop, and in so doing starve, and allow the heat of the 

 sun to kill, a great many of this generation of worms. Follow this 

 by disking and then by either rolling or brush dragging, and 

 a great majority of any remaining larvae will be killed. The ground 



