From Theiler's (1949A) survey of conditions under which the 

 blue tick exists in South Africa she concludes that the most im- 

 portant factor in limiting its spread is increeising aridity. In 

 most parts of South Africa, the critical level is represented by 

 an annual rainfall below fifteen inches. B. de color atus is absent 

 in deserts except for introductions that do not become established. 

 It is present at all altitudes from sea level to high mountains, 

 and can withstand both frost and high terperature. Similar though 

 less detailed observations were reported by A. Theiler (1921). 

 In tropical African forest, the blue tick occurs probably only in 

 open, cleared areas (Theiler and Robinson 195'^). 



The data confirm Lewis' (1939) findings for Kenya, where B. 

 decoloratus inhabits moist regions, highlands up to over 8000 Teet 

 altitude, and forests and glades but seldom open, dry, scrub areas. 

 In Kenya, it is also resistant to heat and cold provided moisture 

 is available. In Ruanda-Urundi the altitudinal range does not 

 exceed 65OO feet (Schoenaers 1951B). 



In the Belgian Congo, Bequaert (1931) fovrnd the blue tick to 

 be so common that it was unnecessary to list all the localities 

 from which specimens were secured. Yet Van Veierenbergh (1954) 

 reports this species as generally distributed in the Congo and 

 Ruanda-Urundi but represented by a small number of specimens or 

 absent from many lots in his collections. The discrepancies in 

 the inferences of these two authors undoubtedly result from dif- 

 ferences in collection areas and methods, interests of collectors, 

 number of ticks taken and hosts examined, and other factors. Sim- 

 ilar situations have provided widely differing reports for the in- 

 cidence of other species of ticks elsewhere, as for instance R. 

 s^. simus on cattle in Nyasaland and in South Africa and R. s."~ 

 "sanguineus on dogs in eastern and southern Africa. It i's o"Bvious- 

 ly in^xjssible to generalize on population abundance in large areas 

 and difficult to evaluate generalizations not supported by data. 

 After having seen Dr. Bequaert *s extensive collections, it should 

 be confirmed that the blue tick is certainly numerous in many 

 Congo areas and that it is uncommon or absent at high elevations 

 and in dense forest areas. 



In Nigeria this is said to be the second most common tick from 

 domestic animals and represented 2Sfo of the specimens collected 

 from domestic animals in all Provinces (Mettam 1951). Only A. 

 variegatum at 45^, is more common in these collections. ~ 



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