THE ALFALFA CATEKPILLAR. 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. 
Eenovate 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 
