October, '12] MOORE: AFRICAN TICK PROBLEM 379 



21 days. The nymph attaches itself to a second host animal and 

 remains for from two to seven days, when it drops off to moult to 

 the adult. The second moult occupies about 18 days. The adult 

 remains on the third host for a period of four to seven days. The 

 larval tick can exist for seven months should it not find a host, 

 the nymph six and one-half months, and the adult nine and one-half 

 months. A. hehrceum also has a life cycle much similar to R. appen- 

 diculatus. Three hosts are sought, the larva remains on the animal 

 from four to 20 days, the nymph four to 20 days, and the adult 10 to 

 20 days. 



H. oegyptium differs from the above species in that the larvae 

 attach themselves to various birds and hares. The larva moults to 

 the nymph while on the bird, but the engorged nymph drops to the 

 ground to moult to the adult. The adult attacks domesticated animals, 

 being often very abundant upon oxen. A. marmoreum differs from 

 H. (rgyptium in that it is the larva or nymph which attacks oxen 

 and goats, while the adult and also the nymph are very common 

 upon tortoises. 



* 'Trekking." Long before any relationship between ticks and disease 

 had been discovered or even thought of, many of the Boers employed 

 methods of ridding their flocks or herds of disease which were really 

 based upon the distribution of the disease transmitting ticks. The 

 High Veld is one of the farmers' favourite grazing sections of South 

 Africa. The average altitude of the High Veld is between 4000 to 

 6000 feet. In. the summer the land is covered with green grass, which 

 makes very good grazing for cattle and sheep. Over this area the 

 ticks which transmit diseases are limited or nearly limited to B. 

 decoloratus and R. evertsi. The reason for this is that the group of 

 brown ticks and the Bont tick cannot withstand the temperature. 

 In the winter the grass dries up and the pasture becomes poor, so the 

 stock farmers started the practice of "trekking" or traveling with 

 their animals to the warm low veld or bush veld, where the grass 

 was abundant. There their animals often took sick from some of 

 the "tick diseases" — especially was this true with the approach of 

 the hot weather. The Boers would then trek back to the higher 

 country, and upon reaching a place where the ticks which caused the 

 chsease could no longer live, the disease would disappear. 



Grass Burning. Grass burning is another early method which 

 was and is even yet often employed to reduce the number of ticks. 

 By burning off the dry grass, the new green grass comes up much 

 sooner and will furnish grazing for cattle and sheep at a much earlier 

 date. Some farmers noticed that after the grass had thus been burned 

 oft, the animals suffered far less from ticks. The practice of grass 



