Diseases, Ticks, and their Eradication. 149 



generally this period averages fifteen days. The second moulting 

 process takes place in the ground, and requires an average period of 

 twenty-four days. In our experiments adult red-leg ticks have jived 

 up to a year, and have after that time attached themselves to a beast. 

 Such longevity seems, however, to be the exceplion, and the usual 

 period is less. 



The Broicn Tick. — Under this name v\'e include the common 

 brown tick {Rh . appendiculatus) and the CaT)e brown tick (Rh. 

 capensis). The European brown tick (RhipicepJialus sangiiinetis) of 

 the dog also belongs to this group ; they all have a similar life-histor3^ 

 The female bro.wn tick, after it has been placed on a host, may be 

 observed to drop already fnlly engorged on the fourth day. and by 

 the end of a week it has usually left the host. The laying of eggs 

 usually begins after six days. The hatching period averages in the 

 warm season twenty-eight clays ; in the winter time the liatching takes 

 several months. The young larvae readily attacli themselves io cattle 

 and engorge rapidly, and may drop oh: the host in as brief a time as 

 three days ; after a lapse of (^ight days all engorged larvae have 

 dropped. The moulting process takes place in the ground and 

 averages twenty-one days. Tiie shortest period recorded was sixteen 

 days. The larvae have in our experiments lived up to a period of 

 •seven months, and the nymphae to six and a half inonths. For some 

 days after moultine; these creatures are not able to feed. They are 

 colourless and weak, and refuse to bite if placed on animals. About 

 a week later they eagerly seek attachment when jdaced on the skin 

 of a host. The nymphae also require a period of about three days to 

 engorge, and within a week have dropped oft' the animal. In summer 

 time these nymphae moult into adult ticks after an average period of 

 eighteen days. Like larvae and nymphae, they are almost colourless 

 and very weak. A few days later they assume the characteristic 

 colour, become more vigorous, but require some time before they will 

 readily attach themselves to a host. In our experiments the adults 

 have been known to live up to a period of fourteen months; thiis is, 

 however, an exception. 



The BJackpitted Tick (Rhipicephalus siinus). — The hatching 

 period of this tick averages thirty days. The larvae do not attach 

 themselves readily to cattle or horses but to other animals, in par- 

 ticular the dog. and the intermediate stages are found on smaller 

 animals. The first moulting usually takes place after twenty days, 

 and the second one, from nymphae to adult, after twenty-five days. 



TJte Font Tick {Amhlyomma hehroeum). —The female begins the 

 laying of eggs in summer time about two weeks after dropping from 

 the host, but under certain conditions over 'hree months may soine- 

 times elapse before eggs are deposited. The shortest hatching period 

 is about ten weeks, but it may last as many montiis; it averages from 

 four to six months. In our experiments larvae have been known to 

 live seven months. The young larvae replete themselves on a host in 

 from four to twenty days', and the majority always drop between the 

 fifth and seventh clay. " The first moulting takes place after twenty- 

 five days, but sometimes four months may pass. The nym];hae 

 replete themselves on a new host in from four to twenty days. Viy 

 engorged nymplme have been known in our experiments to live six 

 months. ' The last moulting process takes place after an interval of 



