THE CATTLE TICK. 
The Cattle Tick. 
By PROFESSOR T. HARVEY JOHNSTON, M.A., D.Sc. 
There are several ticks which may infest cattle, but there is one 
which has such restricted host relationships that we term it the cattle 
tick (Boophilus australis). As a matter of fact, the parasite can infest 
horses and sheep as well, but not to the same extent as it does cattle. 
There is also another tick which is sometimes found on cattle, viz., the 
red-legged tick, Rhipicephalus sanguineus, but it infests certain other 
animals just as readily. Closely related forms to the Boophilus 
australis occur in the United States of America and elsewhere. They 
have essentially the similar life histories, and are capable of transmitting 
the same diseases of cattle. : 
The tick pest obtruded itself on public notice in Australia about 
40 years ago by causing a high mortality amongst certain cattle in the 
Northern Territory. By degrees the tick invaded various parts of 
Queensland, causing at times very heavy losses. The spread was at 
first slow, but by 1895 it had reached the eastern coast. It was not 
till 1906 that the New South Wales border was crossed. The southern 
limit is at present in the Riehmond River district. 
The pest now occurs in practically all parts of Queensland where 
climatic conditions permit its establishment, 7.e., nearly half of the 
State, the Northern Rivers district of New South Wales, the Northern 
Territory, and the north-west of West Australia. 
The life history may be briefly sketched. The engorged adult 
female tick, soon after dropping-from the infested beast, lays about 
1,500 to 2,000 eges—occasionally a great many more. These eggs during 
warm and moist weather—especially during the late summer and 
autumn—hateh out as six-legged larve, which climb up any available 
object, whether it be animals, vegetation, fences, &c., though they do 
not wander very much laterally. Experimental work carried out in 
four localities in Queensland on behalf of the Commonwealth Institute 
of Science and Industry showed that the minimum period elapsing 
between the dropping of the tick and the earliest hatching out of larve 
from the eggs laid by it was seventeen days. The period was usually 
about 30 days in summer and 75 to 90 days during winter in the district 
between Wide Bay and the Tweed River, but in Toowoomba the summer 
period was about 36 to 60 days, while in winter the cold prevented any 
hatching at all. During hot, dry weather most of the eggs failed to 
hatch, and very few larve hatched out from the various experimental 
plots during winter. 
The series of observations showed that if from cattle passing 
through a clean paddock in the coastal districts of south-eastern Queens- 
land engorged cattle ticks were dropped, then such paddock would not 
become infective for other cattle for from three to four weeks in 
summer (November to March or April), and two to three months 
during winter. 
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