BULLETIN OF THE 



No. 45 



Contribution from the Bureau of Entomology, L. 0. 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- 

 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 were driven into " ticky " country. 

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