202 JOURNAL OF THE TRINIDAD 



of the blood is probably little felt and less localised by the animal. 

 If the cattle rubbed these ticks off the irritation would be vastly 

 increased, and the injury would be much greater from the broken 

 mouth-parts remaining in the wounds. 



One is tempted, for the sake of comparison, to refer to the 

 analogous case of scale insects attacking plants. These parasites 

 attach themselves to plants, and, under the protection of a scaly 

 covering, suck the juices of their host. It is again the weakly 

 plant which is attacked, and forms such a capital multiplying 

 ground for the parasites, that it becomes a scaly mass. How do 

 we prevent scale from attacking plants? There is no better 

 preventive that I know than keeping the plant well supplied with 

 good soil, and, in dry weather, with water sufficient. The scales 

 do not seem to be able to make headway on a healthy plant. 

 They are frequently there, bin they do not multiply; they are 

 often attacked by diseases which decimate them and show that 

 they, in turn, are suffering from unsuitable conditions. 



Looked at from this point of view, there is strong ground for 

 adopting the suggestion advanced by Dr. Cooper Curtice, lately 

 of the United Slates Bureau of Animal Industry. In his 

 pamphlet on the "Cattle Tick," referring especially to the form 

 determined as connected with the Texas fever, he writes : — 

 "Almost every farmer in the tick area will ask the investigator 

 why it is that some cattle are literally laden with ticks, while 

 others are free or nearly so. It is usually the fat cattle which 

 enjoy the most immunity. "Whether the ticks thrive better on 

 poor cattle or having attacked an animal cause it to become poor 

 is a debateable question 1 believe that each proposition is true, 

 and that the fat in an animal's skin or the oily condition of the 

 hide has much to do in protecting it against extensive invasion by 

 ticks. It follows therefore that cattle should be kept in good 

 order to resist these pests as will as other diseases." 



"Whether for purely mechanical reasons or from the presence 

 of the obnoxious fat, the health of the animal is supposed to react 

 upon the tick. This view seems to be most reasonable; and, as 

 will be seen later, by far the best way of approaching the problem of 

 the extermination of ticks is to give the animal something in its 

 food which will escape from the pores of its skin and render this 

 objectionable to the ticks. 



The physiological action of the animal's food upon the ticks 

 will explain the fact that cattle taken from poor pastures to rich 

 ones are known to drop their parasites in a very short space of 

 time. 



Mr. Hutcheon. of the Cape Department of Agriculture, 

 remarks : " It is apparent that one of the causes of the prevalence 

 of ticks on cattle on the coast districts is the deficiency of certain 

 food constituents in the sour vegetation there which are necessary 



