VIl Journal of the Department of Agriculture. 



it moults into an adult, which again has to find another host. Pair- 

 ing takes place on the host, and the females drop off when they have 

 gorged. 



Group 3. — Ticks which require three hosts for the completion of 

 their life cycles. To this group belongs the Dog Tick, the Brown 

 Ticks (except Rhlpice-phalu^ bur\^a), the Bont-leg Tick, and the Bont 

 Tick. The larvae of these ticks, having found an animal and gorged, 

 drop off, and, after remaining on tlie ground for some time, moulf 

 into nymphs, which, in turn, have to find another host. Having done 

 so, they engorge, and then drop otf, and, after a lapse of time, moult 

 into adults, which again have to seek another host. Pairing takes 

 place on the host, and tlie females leave tlieii' host Avhen they have 

 engorged. 



All the above ticks do not confine themselves to a single species of 

 animal, and all the stages may be found either on the same kind of 

 animal or on different kinds. In the case of the Bont-leg Tick, how- 

 ever, the larvae and nymphae are not, as a rule, found on the same 

 species of host as the adults. 



The male§ of the ticks belonging to this family remain on their 

 host much longer than the females, and never, except in exceptional 

 circumstances perhaps, drop off their host to find another one, or get 

 on to another animal that may happen to come in contact with its 

 host. 



(1) T/ic Sheep Paialijsis Tick or /'u.^sel Tick (Ixodes pilosus, Koch). 



This species, as one of its vernacular names implies, causes 

 paralysis in sheep, especially in merinos. A single specimen is often 

 capable of producing the malady, but by no means can all individuals 

 of this species produce the disease, as the ticks are often found on 

 perfectly healthy animals. The affection usually occurs in May and 

 June, and is probably due to a toxin which is injected by the tick into 

 the blood of its host when feeding. Animals struck do not often die. 

 and usually soon recover after the ticks have been removed. In 

 removing them care should be taken not to leave the proboscis of the 

 tick in the flesh. 



This species ij> a medium-sized tick (being roughly about the size 

 of the well-known Blue Tick), and can be distinguished by the absence 

 of eyes, and by the presence of a pregenital, a median, a pair of 

 adanal and an anal plate on the ventral surface of the males (fig. 6). 

 and in the female by the presence of an anal groove on the ventral 

 surface. 



The only ticks with which this species is likely to be confused are, 

 with the exception of Ixodes ruhicundns, Neu., the Dog Tick 

 (Haemapliy sails leaclii) and the Blue Tick {BoophiJus decoloratus) , 

 which, apart from lacking the above-mentioned plates in the males 

 and the anal groove in the females, differ in haA'ing a shorter proboscis 

 and palpi. 



The males and unengorged females are reddish-brown in colour, 

 and the engorged females are slate-coloured, and of a peculiar shape — 

 the body being larger behind than in front. 



This tick is chiefly confined to the Cape Province, but has also 

 been recorded from the Orange Free State. It is usually found in 

 grass districts. A variety of this species (var. Jioirardi) is known to 



