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Entomology in the Bitter Root Valley in Montana in June and July, 

 1913. The first experiment, \\ith twenty sheep, was carried out in 

 country known to be well infested with ticks. On the morning of 

 4th June and thereafter until the evening of 14th June, the sheep were 

 put out to graze twice a day for about two hours at each feeding. 

 For the remainder of the time they were kept in corral. About three- 

 fourths of the time the sheep were grazing, they were allowed to run 

 at will, and durmg the other one-fourth they were made to feed in 

 certain places known to be well infested with ticks. During the whole 

 period the development of the ticks was watched, and when it was 

 found that some of them were nearly engorged, the sheep were driven 

 to the camp laboratory and examined, usually twice a day, and any 

 engorged females removed. Two examinations were made of each 

 sheep to locate the hving ticks and to remove the dead ones. The 

 first began on 10th June and was completed on 15th June. The 

 second began on 23rd June and was completed on 27th June. Other 

 less thorough examinations were also made. A table shows the 

 distribution of the ticks recovered from the sheep to be as follows : — 

 Head : 31 dead, 45 alive ; neck : 28 dead, 29 alive ; upper part : 

 30 dead, 15 alive ; sides : 23 dead, none alive ; underneath : 3 dead, 

 23 ahve. 



In certain cases a known number of ticks was placed on a sheep 

 and their subsequent distribution and behaviour were noted. In 

 one of these experiments thirty-three female ticks were placed on one 

 sheep, but only one of them fed sufficiently to lay eggs, though there 

 were six females which stood a fair chance of engorging ; so that it is 

 difficult to estimate what percentage of females that get on to sheep 

 in nature will engorge to repletion. Lambs or sheared sheep would 

 require to be dipped, for the results of the experiments tend to show 

 that such animals present conditions that are favourable for the deve- 

 lopment of the ticks, and kill but few ; therefore if sheep are to be 

 used in the work of tick eradication they must carry heavy wool. 



There are practical difficulties in the use of sheep for this purpose. 

 In the first place, it would be necessary to eliminate temporarily all 

 live stock except sheep on which ticks could be destroyed at weekly 

 intervals by dipping or otherwise ; and, indeed, it is impossible to 

 stock a given area heavily with sheep, and at the same time carry the 

 usual number of other live stock. It would also be necessary to drive 

 the sheep to places in which the ticks are known to be located, 

 for, if left to themselves^ the animals would only go where they could 

 find the best grazing. Finally the possibility that sheep might serve 

 as a reservoir for the virus of spotted fever is a point that should be 

 tested before they are used at all in the destruction of ticks 



It appears, nevertheless, that these animals are good collectors of 

 ticks. Six sheep wdth heavy wool picked up 72 females and 47 males 

 in 11 days, and the author is of opinion that under the same conditions 

 a similar number of horses or cattle would not have picked up and 

 retained nearly so many. Therefore in tick country, which is favour- 

 able for grazing sheep, it would be advantageous to use them as 

 collectors of ticks. By dipping the sheep once in seven days it would 

 seem that much good could be accomplished. But the author is of 

 opinion that the general dipping of all domestic animals remains the 

 most reliable measure tor eradicating ticks. 



(c 2.) A 2 



