June 27, 1895] 



NA TURE 



199 



<lcpcnds the only means of freeing the cattle from these 



pests. 



Thus far the direct eftccts of ticks upon cattle have 

 been considered. Certain alarminy facts have lately been 

 brought to light with regard to the relations existing 

 between ticks and different well-known cattle diseases. 

 The subject is by no means new, having long been a 

 fascinating one for cattle-breeders. The "louping-ill " 

 or " trembling" of the north of Britain has been traced 

 by some directly to the presence of ticks upon the sheep. 

 The same may be said of a disease called "heart-water" 

 at the Cape of Good Hope. Finally, the United States 

 Department of .Agriculture has for the last five or si.\ 

 years been conducting exhaustive experiments upon the 

 connection between ticks and the Texas cattle fever, the 

 results of which have appeared in the annual reports 

 of the Bureau of Animal Industry already referred to. 



There is, in this latter case, present in the blood of the 

 cattle suffering from disease, an infusorian which quickly 

 destroys the red blood corpuscles. This minute organism 

 has also been detected in the body of the tick. It has been 

 again and again transferred from diseased animals to 

 healthy ones by means of the tick, and tick alore. The 

 presence of this infusorian is regarded as diagnostic of 



I he Great Antigua Oold Tic\i.~f/yalomiim venustiim, Koch, (i) M.iturc 

 m.ile, n.itural size ; colours, gold, sc.irlel, and liKick. (la) Magnified 

 %cnlr3l view, (-j) Female, mature but not inflated ; colours, shield 

 hl.^ck with fle.sh-coloured and gold spots ; body dark green. (3) Female 

 full of blood, natural size ; colour, dark green. (4) The same female as 

 in (3), after 20,000 eggs h.ld been laid. (5) Fem.ile into which m.ile had 

 accidentally inserted his proboscis ; both m.agnified. 



the disease ; and the effect of its corpuscle-destroying 

 powers is seen all over the body, as well as in the red- 

 • oloured urine, which has won for tlie disease the colonial 

 name of "red-water." 



Ticks, then, are in certain cases connected with the 

 transmission of deadly disease. In how many more cases 

 this is so remains to be investigated. It is quite possible 

 I hat some of the obscure cattle diseases in different parts 

 if the world are caused by ticks, and that other countries 

 ^^ ill, in their turn, be forced to face this problem. 



There is no«- and then an outbreak of a severe skin 

 disease among cattle in .Antigua ; and this disease does 

 not appear to be known in the neighbouring islands. 

 Jud^'ing from the climate and peculiar conditions of 

 .\ntigua, the scarcity of water and lack of nutritious food 

 fi>r part of the year might be considered sufficient to 

 .iccount for a local disease ; but there is also a large 

 tick present, which has not been recorded from the other 

 islands of the group. A loose theorj' has thus arisen 

 that this "gold tick" is connected with, if not the direct 

 cause of, the cattle disease. 



The evidence available does not tend to confirm this 

 idea, but it is obviously impossible to solve the problem 



NO. 1339, VOL. 52"* " 



in the absence of proper appliances. I was led, however, 

 to commence observations upon the gold tick, which may 

 be of interest. 



Mr. A. D. Michael has determined it to be Hyalomiiia 

 vcniistwn, which Koch described in 1847 from a single 

 male specimen collected in Senegal. There is a local 

 tradition in .Antigua that the tick was introduced some 

 thirty or forty years ago with some imported .Senegal 

 cattle ; and this determination lends probability to the 

 belief The male is a very beautiful creature, decked in 

 scarlet and gold, whence he obtains his name. The 

 female is very large, one specimen being nearly an inch 

 in length and weighing '17 oz. 1 calculated the number 

 of eggs laid by this female at over 20,000. She com- 

 menced laying on July 31, and finished, a shrunken mass, 

 on September 10 — a period of exactly six weeks. The 

 accompanying life-size drawings are of Antigua gold 

 ticks. The first is a mature male. He is not usually 

 larger than this, and may be seen moving rapidly across 

 the ground, or firmly attached to the skin of the cattle 

 close to a female. The next three figures are of females, 

 all mature, but at different stages. The first is undis- 

 tended ; the second gorged with blood, and commencing 

 to lay its eggs ; while the third is the same tick after 

 the last egg was laid. There is also the drawing of a 

 curious case, in which a male had by accident attached 

 himself to a distending female — a mistake which resulted 

 in the premature death of both. 



The period of incubation observed in the tick's eggs 

 \aried from twenty-three to fifty-one days. The young 

 ticks usually emerged in great numbers on the same day, 

 and any eggs left unhatched quickly dried up. In An- 

 tigua the gold ticks appear upon cattle, in numbers, from 

 May till September each year. It became important to 

 determine what became of them in the meantime ; and 

 whether they passed the winter in the body of the parent, 

 in the egg, or as young ticks. From experiments in the 

 laboratory, it would appear that the little ticks pass the 

 winter months huddled together in masses of several 

 hundreds at the roots of the old dead grasses. 



In considering the remedies for ticks, one is soon forced 

 to the conclusion that direct measures against the parasite 

 themselves will be of little avail. Methods of pre- 

 vention are always preferable to those of cure, and in 

 no case is this more so than with parasites of this class. 

 Besides this, they are practically invisible at the most 

 dangerous stage ; and when we see the ugly, swollen, 

 mature specimens, we know that their evil work is dont^ 

 All large females should be carefully collected and burnt, 

 however, as thus future attacks will be diminished. 



The treatment of pastures is a very important matter. 

 Here probably the parasite spends the greater part of 

 his early life — usually on the ragged bunches of old grass 

 left from previous years. The proper feeding or cutting 

 of the grass, and the liming and draining of the pastures, 

 will destroy myriads of the infant ticks or "grass-lice." 

 For the sake of the animals, there is every inducement 

 to render the pastures as nutritious as possible : and 

 ticks do not seem to trouble the sleek cattle of the herd. 

 It is an undoubted fact, moreover, that the improvement 

 in food, due to change of pasturage, does in certain cases 

 cause all the ticks to drop off infested animals. The first 

 class of remedies will aim at cutting off the supply of 

 ticks by treating the pastures. 



The second class — one might say almost the only one 

 which is attempted in the tropics- is the destruction of 

 ticks upon the cattle. 



The common method of tying the legs of the animal 

 together, hurling it to the ground, and smearing some 

 tick-destroying compound over it, cannot be too strongly 

 condemmed, especially as there is no need for- it 

 whatsoever. Cattle may be handled with impunity if 

 some form of cattle-bail is employed ; by this means they 

 may be driven one by one into a small trap, where they 



