CONTROL OF TICKS 443 



addition of soap and kerosene oil. This was devised by Watkins-Pitchford 

 for the frequent dippings necessary to destroy ticks in South Africa. It 

 has been utilized also by the Bureau of Entomology in the weekly dip- 

 ping of animals against the spotted-fever tick. The destructive effect 

 of the material on the tick is increased and the caustic action on the 

 host IS reduced by this addition. This formula is as follows, English meas- 

 ure: Arsenite of soda (80 per cent arsenious oxide) 81/. pounds, soft 

 soap 51/2 pounds, paraffin (kerosene oil) 2 gallons, water 400 gallons 

 It IS nnportant that the proper strength of the solution be main- 

 tamed at all times, both to secure efficiency in tick destruction and to 

 avoid injury to the stock. A simple outfit has been devised by the U S 

 Bureau of Animal Industry for determining the percentage of arsJnic 

 present. 



To accomplish the eradication of the cattle tick the frequency of 

 dipping IS important. It should never be longer than the period required 

 for the ticks to become mature and drop from the host. This is about 

 20 days. Usually it is safer to dip at intervals of two weeks. Eradication 

 may be accomplished if systematic dipping of all stock is kept up for a 

 period of about six months in the summer, or sufficient time to allow all of 

 the seed ticks which have not gained access to the host to die of starva- 

 tion. Thorough dipping of every individual is important; the animals 

 should be completely submerged. 



Owing to the poisonous effect of arsenicals, both when taken internally 

 and under certain conditions when applied externally, the following pre- 

 cautions should be exercised in dipping live stock. Have the bath of the 

 proper strength, water the animals a short time before dipping, avoid 

 heating the cattle by long drives or otherwise just before or after dipping 

 dip during the cool part of the day or provide shade when convenient.' 

 The latter point is not nearly so important in connection with the use of 

 arsenicals as with oil dips. The poisonous effect of arsenicals has been 

 mentioned m dealing with the control of cattle lice. It need not be dwelt 

 upon further here. It is certain that dipping in arsenical solutions is 

 the most satisfactory method of destroying ticks and lice of all kinds on 

 cattle and horses, and the experience of stockmen in the South in con- 

 nection with the cattle tick eradication indicates that, if the proper 

 precautions are exercised, thousands of cattle may be dipped without the 

 loss or injury of even a single animal. 



The Rocky Mountain Spotted Fever Tick.— As was pointed out in 

 the lecture upon the biologies of ticks this species has the habit of drop- 

 ping from the host for each of its molts. It also develops on a large 

 number of different species of animals, but the adults, especially in the 

 Bitter Root Valley where the disease is the most virulent, practically all 

 engorge on the larger domestic animals. This species appears to be 



