28 PRELIMINARY REPORT OX ALFALFA WEEVIL. 



25th of May, and observations made at the time indicate that while 

 many of the full-grown larvae were collected, most of the smaller 

 ones were left among the buds. On May 29 the field received a 

 second irrigation. The larvae at this time were very abundant; the 

 gathering machine, too, had retarded the growth of the plants by 

 breaking off the growing tips and some of the plants themselves had 

 been broken down by the collecting machine. As a result the alfalfa 

 had apparently made little or no growth since about the 22d, and its 

 value as forage was at that time rapidly decreasing. 



A wire-brush machine (PL VI, fig. 1) was constructed by Mr. L. 

 Hemenway by bolting about 30 pieces of Xo. 8 steel wire 7 inches 

 long between iron clamps on each spring tooth of an old spring-tooth 

 cultivator. The ground was gone over with one of these on June 1, 

 as soon as the hay had been removed. The jumping action of the 

 spring, together with the wire brushes, proved very effective in crush- 

 ing larvae and pupa? among the stubble. The field was then gone 

 over with a plank leveler, shown in Plate VIII, figure 2, with square 

 iron edges bolted to a plank. June 7, the field received another 

 brushing with the wire-brush machine, which crushed cocoons and 

 larvae. By June 13 the second crop in this field had started nicely 

 with very few weevils present. In another field near by no attempt 

 had been made to treat it or to remove the weevil, and this field was 

 taken as a check on the one under treatment. An examination at 

 this time showed that when the former field was in good condition, 

 with few larvae, the field that had received no treatment was bare 

 and brown from their attack. 



On June 22 the second crop of alfalfa on the treated field was about 

 8 inches high, while the unworked field was still bare and its condi- 

 tion, on June 27, is shown in Plate VI, figure 3. By the 27th the 

 alfalfa in the treated field was about 1 foot in height (see PL VI, 

 fig. 2), the stand extra good, and the treatment had seemed to free 

 the field from weeds and other foreign growth. By July 7 the plants 

 were about 2 feet in height, while, of course, both the adults and 

 larvae could be found to some extent in this field. July 27 the second 

 crop harvested 2 tons per acre, selling at $9 per ton in the field. The 

 field at time of harvest of second crop is illustrated in Plate VII, 

 figure 1 . The unworked field, however, was making an inferior second 

 crop, coming just a little in advance of the third crop in the treated 

 field. 



From the treated field there was also a fourth crop of hay secured. 

 The field was photographed on October 9, 1911, and the yield of hay 

 is illustrated in Plate VII, figure 2. The condition of the check field 

 a few days later, October 12, is shown in Plate VII, figure 3; here the 

 second and third crops were both not only badly damaged, but so 

 delayed in growth of alfalfa that, as shown by the illustration, no 

 fourth crop was secured at all. 



