BULLETIN OF THE 
No. 45 
Contribution from the Bureau of Entomology, L. O. Howard, Chief. 
November 22, 1913. 
EXPERIMENTS IN THE USE OF SHEEP IN THE ERADICATION 
OF THE ROCKY MOUNTAIN SPOTTED FEVER TICK. 
By H. P. Wood, 
Bureau of Entomology. 
PLAN OF EXPERIMENTS. 
In order to test the destructive power of sheep against the spotted 
fever tick and to ascertain what importance sheep might play in the 
practical eradication of the tick, some experiments were performed 
by the Bureau of Entomology in the Bitter Root Valley in Montana 
in June and July, 1913. This work followed the announcement to 
the Montana State Board of Entomology, by Dr. L. D. Fricks of the 
Public Health Service, of observations on the death of ticks on sheep 
which have been published in the Public Health Reports of August 
8, 1913. 
Two experiments were performed, one with 20 sheep and the other 
with 2 sheep. The first experiment, with 20 sheep, which included 
1 ram, 11 other adult sheep, and 8 lambs, was performed in country 
known to be well infested with ticks. The country over which the 
sheep ranged is adjacent to the foothills and is well supplied with 
bushes of various sorts, a growth of small pines, a few fairly large 
trees, and several streams of water. There was an abundance of 
grass along the streams, but under the pines next to the foothills 
there was little grass. In the ravine between two hills there was 
a thick growth of brush. It is next to the foothills, where brush 
abounds, that the ticks were found most abundantly. Very few 
ticks were observed along the streams and where the grass was grow T - 
ing in abundance. 
Previous to the time the sheep were driven onto a school section 
which was used as an experimental pasture, they had been ranging 
away from the foothills and were probably quite free of ticks. No 
ticks were seen on cattle and horses running in the range from which 
the sheep were taken during the whole tick season, and the animals 
were under close observation by the owner. It is fair, then, to sup- 
pose that there could have been few, if any, ticks on the sheep at the 
time they w r ere driven into " ticky " country. 
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