FIELD EXPERIMENTS IN DESTROYING WEEVIL. 27 



indicate, however, that the brush drag does not destroy as many of 

 the larvae as one would suppose, and for this reason some harsher 

 measures have been put into application during the season of 1911. 



Street-Sweeper Experiments. 



The ordinary street sweeper, such as is used in our cities, appears 

 to be a most thorough measure of destroying the pupae. This much 

 was determined by the Utah Experiment Station. A street sweeper 

 (PL V, fig. 1) was used in a field on June 22, 1911. While examina- 

 ation showed that the result of this treatment, at this time, was to 

 kill most of the larvae and pupae, it did not kill a great percentage of 

 the adult weevils, which had already developed in large numbers. 

 It would have been much better had this work been carried out about 

 two weeks earlier; not only the condition of this field but of others 

 in the neighborhood treated between June 14 and July 1 indicated 

 that considerable good had resulted from this treatment even at this 

 late season. On another farm, owned by Mr. Breeze, southwest of 

 Salt Lake City, a field was swept with the street sweeper about the 

 14th of June with a view of interfering with the work of the weevil. 



By July 7 the alfalfa in the Breeze field was about 20 inches high 

 with very few weevils present. (See PI. V, fig. 2.) Twenty days 

 later the alfalfa was 30 inches high and in full bloom, being ready for 

 the taking of a second crop. Just across the road from this farm 

 was a field where no treatment whatever had been applied against the 

 weevil. In this field the alfalfa plants were only about a foot in 

 height and very much delayed (PL V, fig. 3). This seems to indicate 

 that as a protection for the second crop the measure has considerable 

 value. The drawback here is in the expense of a street sweeper, 

 although of course where the members of a community club together, 

 or in case of very large alfalfa fields of several hundred acres, the 

 first cost of this sweeping machine would not constitute such an 

 important item. 



Wire-Brush Experiment. 



A 13-acre field of alfalfa 7 years old had been disked in the spring 

 of 1910. The first crop of alfalfa was reported to have been reduced 

 to one-half by attack of the weevil. A weevil-collecting machine 

 had also been used on this first crop, but there were still enough of 

 the weevils left in the field to greatly retard the second crop. It was 

 disked and dragged again and a fairly good yield of the second crop 

 was secured. This was also true of the third crop in this same field. 



On May 15, 1911, there was a good stand of alfalfa in this same 

 field. One irrigation had at this date been applied. The plants 

 were a little over a foot in height, and while at the time, May 15, they 

 were in fairly good condition they were heavily infested with weevil 

 larvae. The gathering machine was used twice between the 17th and 



