148 Journal op the Department of Agriculture. 



process from the nymphal to the adult stage takes place in the oTomid, 

 and the sexes meet again on the host. 



TJiirdly. — Ticks which require three hosts for the completion of 

 their life-cycle. To this group belong the brown licks (RJiipiccphaius 

 (ippendiculatus), the black-pitted tick (R. siinus), the Cape brown 

 tick (R. capensis), the European brown tick (R. sanguineus), the bont 

 tick (Amhlijoinma hehraeum) , and tlie dng tick (Haemaphy.^alis leachi). 

 The larva reaches the animal and engorges, and as soon as it has 

 done so drops to the gTound, where it moults (after a lapse of a certain 

 time) into the nymphal stage. The nynipha seeks a second host, also 

 engorges, and after repletion drops to moult into the adult on the 

 ground. The -sexes seek a third host, where tii'\v n;eet and the whole 

 life-cycle begins again. 



Of interest to us from our point of vieAv arc ibe dates reqaiicd — 



(1) for laying the eggs and hatching into larvae; 



(2) for the completion of the life-cycle on the host in the case 



of the one-host tick (the blue tick) ; 



(3) the time the larvae and nymphae require to replete on a 



host ; 



(4) the length of time the engorged lar\ae and nymphae 



require to moult on the ground ; 



(5) the length of time the adult femab^s remain on the host 



before they drop ; and 



(6) the length of time these various ticks and stages of ticks 



may live. 



Concerning these the following facts are kn(>v>n : — 



Blue Tick. — Tlie whole length of time lliis tick requires from 

 larval to adult stage averages three weeks. From the third week the 

 engorged blue females begin to drop, and about the end of the fourth 

 week the greater number has left the host. In other words, wlien we 

 remove an ox or a horse out of the veld and place it in a stable we 

 must constantly expect, during the four following weeks, the 

 ajjpearance of blue ticks whicb have attached tliemselves up to the 

 day when the animal left the veld. This applies to the suiijmer 

 season only; in the winter it is delayed. The eggs hatch in the 

 warmer season in about three to six weeks, and on an average ai'ter 

 about thirty-six days; in the winler it will take longer. The young 

 larvae kept in g-lass bottles have been known to live six months. If 

 they do not reach a host they die; on reaching the host they continue 

 the life-cycle. During this time they sit on the grass. No food is 

 obtained from the plant (as the popular belief is), +lierefore it follows 

 that the blue tick must finally die if no host is found after the above- 

 stated lapse of time. 



The Red-leg Tick. — The hatching period of Hie eggs of this tick 

 is (in summer) about thirty days on an average. We have known the 

 young larvae to live for a period of seven months. The young- 

 larvae which find a host" generally hide themselves in the 

 interior of the ear, rarely in the flanks, and soon begin to replete. 

 They undergo the change from larvae to nymphae on the liosl. The 

 nymphae attach themselves near the place where the larvae were and 

 replete themselves quickly, so that as early as leu days after attach- 

 nient of the larvae the nymphae may be 'eplete and dro]), but 



