THE AGRICULTURAL NEWS. 



How Ticks are Killed 



When Cattle 

 Are Dipped or Sprayed 



■If Hf 



A knowledge of how a dip is absoltxd by Ticks wKen cattle are <lipped or sprayed with an anenieal wasK is of great assistance in elucidating the 

 problem ot Tick desiruclion. Although this subject has given rise to much conjecture, very little definite information is obtainable as a result of practical 

 experiment. Work directed by William Cooper and Nephews in South Africa has, howerer, furnished results from which feasible deductions have been 

 made, and these appear to throw some light on the subject. 



The theories advanced by different workers are : — 



1 . That the Tick absorbs the poison through its ovm skin during the process of dipping or iprayiag. 



2. That the absorption of the poison through the skin of the Tick takes place after the operation of dipping or spraying is completed. 



3 That the poison is absorbed by the skin of the animal, and that the Tick sucks in the pcnson with the fluids extracted while feeding on 

 the animal. 



It follows from No. I theory, and it is asserted by those who favour this theory, that the longer the period of immerrion of the animal m the tick-killing 

 Juid, the more certain is the destructive effect on the Ticks. For this reason the supporters of this theory advocate a dipping bath with a long swim. 



As a result of the work carried out under the direction of William Cooper and Nephews, it has been established that a brief, thorough immersion of 

 the animal kills the Ticks as effectively as a long one. That is to say, complete immersion for a comparatively short time, ensured the death of the Ticks. 



If Ticks are taken off cattle soon after they have been dipped or sprayed with an arsenical wash, and are thoroughly cleaned to remove any externally 

 adherent arsenic, their bodies are found to contain no traces of the poison, whilst Ticks similarly removed on each of the six days following dipping are 

 found to contain appreciable quantities of arsenic, thus proving that the arsenic is absorbed after the operation of dipping or spraying is completed. 



With regard to theory No. 2, it is highly improbable that the arsenic is absorbed through the skin of the Tick, for the fluid dries on the skin in less 

 than an hour after treatment, during which period, as was shown in the previous paragraph, no absorption takes place. 



There only remains then theory No. 3, viz., that the host animal absorbs the poiaon mto iu skill, and later, the Tick imbibet the poison during the 

 process of feeding. All experience -with dips in the 6eld goes to support this theory. 



Given dips which contain equal amounts of the poisonous agent, it has been proved by actnal experiment that those which spread over and thoroughly 

 wet the whole surface oP the skin of the animal possess the greatest kiBing powtr. Therefore, an essential feature of a dip is that it should give coirjplete 

 and uniform penetration over the whole skin surface of the anim a l . 



It is a proven fact that those dips which salorate the skin b patches kill only the Ticks which adhtfe to tltose patdtes. It u (onnd, moreover, -that if 

 a solution of arsenic is injected subcutaneously, die Ticks attached aroand the site of the injection are poisoned, and although they have had no contact 

 with arsenic from the exterior, their remains are foond to contain appredable quantities. This poisonous action it limited to an area of about 6 inches radius 

 from the site of inoculation. 



Investigations have shown that arsenic applied to the undamaged skin of an aniaal does not appear in appreciable quantities in the internal organs of 

 the body. This seems to prove that the arsenic which is absorbed by the skin fails to reach the circulating blood which would carry the poison from the 

 surface to the interior. The accumulated facts which have resulted from enquiries into the matter lend the greatest support to the theory that the hving 

 cells, which form the deeper layers of the skin, have an actual affinity lor arsenic, and the poison is arrested and fixed in them and thus prevented from 

 reaching the circulating blood. If this theory is correct, then after dipping or spraying, the deeper layers of the skin will become strongly impregnated 

 with arsenic, possibly in a state of combination with the organic tissues. It is then easy to suppose that while feeding on a beast which has been recently 

 dipped or sprayed, the tick takes in considerable quantities of the poison with the blood and lymph which have necessarily passed through iheac deeper 

 layers of the skin, which are more or less saturated with arsenic^ 



COOPER'S CATTLE TICK DIP , 

 Hmt nemved the official approoal of th» foUvmng Comntrimt 



(hlloD of South Africa, Northern Rhodesia, Brazil. Basutolud, 



Nyasaland, Swazifaad, Southern Rhodesia, Madajascar, 



British East Africa, German East Africa. Portugaeae Eaat Africa. 



J>ertuguese West Africa, Egypt. Arjcntine Republic, Qaeeaslaad, 



Initrd States of America, New South Wales, 



Northern Territory of Australia. 



WEST INDIAN AGENTS ; 



n.KtrrS: S. L. Horslon* & Co. ANTIGUA: Bennett. Br. »0D « C«. 



JAMAICA: D. Henderson & Co., Kingston. 



ORBNADA: Thomson, Hankey & Co. 



BASBAU05: Barbado.s Co-operative Cotton Co., Ltd. 



UAMAMAS: W. N. Twynam, Nas.sau. 



TRINIDAD: T. Oeddes Grant. Port of Spain. 



BRITISH GUIANA: Sandbach, Parker & Co. 



ST. V)NCl:NT: Corea & Co.. Kingstown. NEVI5: -S. D. Malnne. 



DANISM WEST INDIES: A. Schmlegelow, St. Croix. 



M0NT5ERRAT: \V. Llewellyn Wall. DOMINICA: Hon. H A. Framplon. 



ST. Ll!CIA: tiarnard Sons & Co.. Castries. ^ 



Munifacl.irers : WILLIAM COOPER & NEPHEWS, Berkhamsted, England. 



IKAMjlL."^ Toroaio. CLicjjc. Syditj, Mclkgaraa, Aucklaad. Bneaw Airn, Mottt V.dto. Punta Arenas. East London. Odeau. 



