TEXAS FEVER. 147 



dered immune by mild attacks of the disease before they became 

 fully susceptible. If it is true that immunity can only be secured 

 through an attack of the disease it follows of necessity that the 

 only preventive is the exclusion or extermination of the tick. 



The ticks on any pasture or farm may be easily and quickly 

 exterminated and the farm easily maintained free from ticks. 

 Hence, it is possible, if not yet practicable, to exterminate the 

 ticks over the entire South and maintain the country tick-free. 



METHODS BY WHICH TICKS MAY BE EXTERMINATED. 



1. Keep all cattle, mules and horses out of the tick infested 

 pasture, lanes, and lots for one season, or at least, after Septem- 

 ber 1st, and the ticks will be exterminated by the next spring. 



2. Divide the pasture by a fence, with a rail or board tight 

 on the ground, and keep all cattle, mules and horses out of one- 

 half this year after September ist, and out of the other half next 

 year, and the work of exterminating the ticks will have been ac- 

 complished. 



3. If possible burn the pasture over thoroughly, in the spring. 

 Mix sulphur with the salt given the cattle — one part of sulphur to 

 three of salt. Begin not later than April 15th and grease the legs 

 and under parts of the body of all cattle, once a week, all sum- 

 mer. In greasing look carefully for any ticks that may have es- 

 caped the grease or attached themselves to the upper parts of the 

 body. If any are found pick them off and burn. The grease 

 should be one-third kerosene and the other two-thirds any cheap 

 sort available. If a little sulphur and tar be added the effect 

 may be improved. 



This third method requires considerable care and thorough, 

 regular work to make it effectual and is only practicable when 

 the number of cattle is not too large. 



Concerning the life history. — The methods just given are 

 based on the following facts concerning the life history of the 

 tick : The full-grown female tick drops off the cattle when she 

 becomes engorged with blood. Her heavy body and small, short 

 legs make crawling difficult, so she gets under the dry grass, or 

 "trash" close at hand. In two or three days she begins laying 

 eggs and lays from 1,500 to 2,500 during the next two weeks. 

 In very warm weather, under the most favorable conditions, these 



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