iDisBASEs, Ticks, and their ^Eradication. 155 



repeated every third day and is continued as long- as the different 

 stag'es can live in the grass, viz., at least a year. 



In the case of the bont tick, which also requires three different 

 feedings on an animal, the case is very similar to that of the brown 

 tick. The larvae remain on the animal from about four to five days, 

 the nymphae about the same period, and the adult about a fortnight. 

 To be most effective, therefore, dipping would have to be done at 

 least about every four days. 



From the above notes it will be seen that dipping at long intervals 

 is not effective in the destruction of the red, brown, and bont ticks. 

 If dipping is adopted to eradicate a disease transmitted by brown or 

 bont ticks it must be repeated at short intervals. The intervals 

 between dippings should not exceed the periods' of attachment of the 

 ticks on the animal ; in order to catch all ticks intervals would have to 

 be as short as three days. In practice it has been proved that dipping 

 at intervals of five days is effective when supplemented by hand- 

 dressing of the depths of the ear, the sheath, anus, and brush. 



Once dipping is commenced it will have the effect of destroying 

 most ticks during the first few months. It is advisable to continue 

 the dippings energetically during the summer time. All changes in 

 tick-life take place more rapidly during this season, and ticks eagerly 

 seek attachment on the cattle. This season ought to be selected for 

 the dippings at short intervals. Lounsbury and Dixon were the first 

 to observe that arsenite of soda can advantageously be used for the 

 eradication of ticks. The dips which were subsequently more 

 frequently used are known as " laboratory dips." They were intro- 

 duced by Pitchford in Natal, who designed dips for an interval of 

 three days, seven days, and fourteen days. 



The formulae are as follows : — 



3 Days' 7 Days' 14 Days' 



Interval. Interval. Interval. 



Arsenite of soda, 80 per cent. ... 4 lb. 8 lb. 12 lb. 



Soft soap 3 lb. 6 lb. 6 lb. 



Paraffin 1 gal. 2 gal. 2 gal. 



Water 400 gal. 400 gal. 400 gal. 



The arsenite and soft soap are dissolved separately in sufficient 

 hot water, the soap and paraffin beaten into an emulsion, and the 

 arsenite solution then mixed in. Cold water is then added to make 

 up the 400 gallons and the whole is stirred vigorously. Most farmers 

 now omit the soft soap and paraffin and use a plain aqueous solution 

 of arsenite of soda, adhering to the strength laid down in the Pitchford 

 formula and using 1 lb., 2 lb,, or 3 lb. per 100 gallons of water 

 according to whether three-day, five to seven day, or fourteen-day 

 dipping is contemplated. 



The reason for the different strengths of dip at different intervals 

 is of course, in the first instance, a consideration for the animal to be 

 dipped, a weaker solution interfering less with its skin and health 

 than a stronger one. The different species of ticks and the various 

 stages show a different resistance to arsenic — some are killed more 

 easily than others. From the point of view of East Coast fever the 

 three-day dip has not always proved to be effective, and instead a 

 seven-day dip strength used in five days' interval, supplemented with 

 hand-dressing, is now frequently made use of, and with success. 



