486 



DISEASES OF CATTLE. 



ture, or those which hatch from eggs laid by females already there, 

 will all eventually meet death. Such of these as get upon the cattle 

 from time to time will be destroyed by the treatment, while those 

 which fail to find a host will starve in the pasture. 



Animals may be freed of ticks in two ways. They may be treated 

 with an agent that will destroy all the ticks present, or they may be 

 rotated at proper intervals on tick-free fields until all the ticks have 

 dropped. 



PASTUEE ROTATION, ETC. 



Time required to hill ticks hy starvation. — The time required for 

 the ticks to die out after all animals have been removed from infested 

 fields and pastures varies considerably, depending principally on 

 climatic and weather conditions. The dates when pastures will be 

 free of ticks, beginning during each month of the year, are given in 

 the following table : 



T'nnr required to free pastures from ticks hy starvation. 



Dale of removal of all animals 

 from pasture. 



Julyl 



Aug.l 



Sept.l 



Oct. 1 to Nov. 1, inclusive 

 Dec. 1 



Date when pas- 

 ture will be free 

 from ticks. 



Mar. 1. 

 May 1. 

 July 1. 

 Aug. 1. 

 Aug. 15. 



Date of removal of all animals 

 from pasture. 



Dec. 15 to Mar. 15, inclusive 



Apr. 1 



Apr. 15 



May 1 to June 15, inclusive. 



Date when pas- 

 ture will be free 

 from ticks. 



Sept. 1. 

 Sept. 15. 

 Oct. 15. 

 Nov. 1. 



The table above is based on investigations b}'' Hunter and Hooker ^ 

 at Dallas, Tex., and by Graybill ^ at Auburn, Ala. All the periods 

 obtained bj^ Newell and Dougherty (1906)^ in work carried on at 

 Baton Rouge, La., which is much farther south, are shorter. The 

 periods above should be found ample for all localities lying no far- 

 ther north than Dallas, Tex., or Auburn, Ala. For many localities 

 in the southern part of the infested region the periods necessary to 

 starve out an infestation are no doubt somewhat shorter than those 

 gi^'en above. In general, moisture and cold prolong and dryness and 

 heat shorten the duration of an infestation. If various portions of 

 the same pasture differ with regard to temperature and moisture, as is 

 frequenth'^ the case, some parts become free of ticks before others do. 

 Other things being equal, high, dry, unshaded land becomes tick 

 free sooner than low, damp, shady land. 



The simplest and safest plan in most cases, however, is to follow 

 the foregoing table in the region indicated for it. It is probable that 



^Bulletin 72, Bureau of EntomoloKy, TJ. S. Department of A{;iicnlture. 

 'Bulletin l.TO, Bureau of Animal Industry, U. S. Department of Agriculture. 

 ' Circular 10, State Crop Pest Commission of Louisiana. 



