Life cycle figures published by Wilson (1950B) for Nyasaland 

 fall well within the above limits. Lewis (1939B) in Kenya found 

 that larvae and nymphs remain on their host for several days 

 longer than the above periods. 



Females in Nyasaland engorge and oviposit only during the wet 

 season when the relative humidity is above 1%. Adults, especially 

 engorged females, are rare at other times of the year. Unengorged 

 larvae die in large numbers during the cool, dry months of the year, 

 but nymphs are common at this season. Under optimum conditions of 

 high humidity, 110 to 129 days are necessary to produce adults of 

 the Fi generation in Nyasaland (Wilson 19^4,19A6,1950B) . 



The life cycle in Northern Rhodesia is much like that of A. 

 variegatvim (Matthysse 195^), although adult brown ear- ticks are 

 more severely restricted to the wet season. No adults appear until 

 November, when they reach a high peak of abundance, but their num- 

 bers drop rapidly in the dry season, late March and early April, 

 and until October adxilts are rare. In some areas, however, a few 

 adults persist through the dry season. Larvae are not found until 

 late in the rainy season, late Februarj?^, and are abvindant from 

 March throijgh August. Laorval and nyraphal incidence overlaps from 

 early April through August, but nymphs rapidly disappear with SepL- 

 tember's hot weather and are completely absent by early November. 

 Incidentally, adults of R. compo situs (= R. ayeri ) preceed those 

 of R. appendiculatus , being abundant in September and October and 

 present in some numbers in July, August, and November. This may 

 have some significance in maintaining and transmitting East Coast 

 fever in cattle when adult brown ear-ticks are absent. 



In laboratory studies on the effect of artificial climates 

 (Mulligan 1938), engorged females proceeded to oviposit when re- 

 turned to a temperatiire of 24°C. to 27°C. after having been ex- 

 posed to 1°C. to Zk°C. for eight or nine days. Many of the re- 

 sulting eggs shriveled and died; some larvae that hatched did 

 survive but many others succumbed. Eggs hatched after having 

 been exposed to the same low temperatvure range for six hours. 

 About half of the engorged larvae subjected to the low temper- 

 ature failed to molt and died. 



The sxirvival of ticks, whether fed or unfed, is of practical 

 importance. Lewis (1939B), working in Kenya, has recorded the 



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