6 
COLOEADO Experiment Station 
summer range. The sheep, according to Mr. Fowler’s statement, 
had been on the driveway for tour days, and had had only about 
one-fourth rations. When they reached Death Valley another 
owner ahead asked Mr. f owler to hold his band an hour or two 
so as to prevent the two bands from mixing. The sheep grazed 
over the area since found to be badly infested with milkweed 
for about two hours, and at the end of that time they began to 
die. Two hundred and twelve head were dead before night. 
In November, 1917, Mr. R. E. Walker pastured 900 head 
of ewes across the milkweed-infested field. Whorled milkweed 
constituted about all of the available forage at the time. The 
band was held on this patch for some time and 780 head died 
within twelve hours with the same typical poisoning symptoms 
shown by the sheep previously lost at this place. Figures 1 and 2 
Fig'S. 1 and 2 — 780 head of sheep out of 900 -were poisoned here in one day. 
do not show the sheep after they were dragged together, but as 
they actually fell. Four hundred were pulled out of the main road 
to allow cars to pass. 
This series of losses at one place and under practically the 
same conditions led to the sending of the writer into the field 
in the spring of 1918 to establish the identity of the plant caus- 
ing the trouble and to work out its distribution and efficient 
methods of control and eradication. 
This work has been carried on during the summers of 1918 
and 1919 and the data so far obtained has shown that the milk- 
