TEXAS FEVEK. 



487 



the periods given in the table should be lengthened a little for the 

 northern part of the infested region. The experiments conducted 

 thus far in various places indicate this, and it will place the eradica- 

 tion work in that region on the safe side. For example, E. C. 

 Cotton 1 obtained at Knoxville, Tenn., records for September and 

 April somewhat longer than those given above. They are as follows : 

 Cattle removed April 15 ; pasture free of ticks November 13. 

 Cattle removed September 15 ; pasture free of ticks July 18. 



In localities with temperature and other conditions similar to those 

 at Knoxville, Tenn., these periods should be followed. 



Time required to render- cattle free of ticks when placed on unin- 

 fested fields. —Before discussing plans for rendering farms tick free, 

 involving the use of the information given in the foregoing table, it 

 will be necessary to indicate how animals may be entirely freed from 

 ticks by placing them on uninfested fields. This is based on the fact 

 that the female tick must drop from the host to the ground before 

 eggs can be laid and before young ticks will develop. 



The shortest time in which seed ticks will appear after engorged 

 females have been dropped is 20 days. Consequently cattle placed 

 on a tick-free field during the warmer part of the year are not in 

 danger of becoming infested again with young ticks until 20 days 

 have elapsed. The time required for all the ticks to drop after cattle 

 have been placed on uninfested land varies with the temperature, 

 being much longer during the winter than during the summer. The 

 time required, beginning at various times of the year, is given in the 

 following table : 



Time required for all tiels to drop from ealtle placed on tick-free land. 



When ticky cattle are placed on 

 ticli-free land during — 



August 



September 

 October . . 

 November. 

 January. . . 

 February . . 



All ticks will 

 have dropped 



Six weeks. 



Do. 

 Eight weeks. 

 Nine weeks. 

 Ten weeks. 

 Seven weeks. 



When ticky cattle are placed on 

 tick-free laud durmg — 



March 

 April.. 

 May.. 

 June. . 

 July.. 



All ticks will 

 have dropped 



Seven weeks. 

 Six weeks. 



Do. 



Do. 

 Five weeks. 



Freeing cattle of ticks hy rotation on tick-free land. — The plan of 

 freeing cattle of ticks by rotating them from one lot or field to an- 

 other is as follows: Beginning at any time from February to Sep- 

 tember, inclusive, the cattle are removed from the tick-infested pas- 

 ture to a tick- free lot or field and kept there for not more than 20 

 days. During this time a considerable number of ticks will drop. 

 In order to prevent the cattle from becoming reinfested (by seed 



' Bulletin 81, Agricultural E.xperiment Station of the University of Tennessee. 



