148 COMMON DISEASES. 



eggs hatch in about three weeks. The period may be prolonged 

 for eight weeks, or indeed, the hatching prevented entirely if the 

 weather is sufficiently cold. 



The young ticks when first hatched are very small, being 

 scarcely visible. They crawl up the grass, weeds, or small twigs 

 and there wait for the cattle to come along. If the cow does not 

 come along for three months, he will still be there waiting for her. 

 If no cow, mule, or horse comes along in three or four months 

 these small ticks die from starvation, for they have no other 

 known means of obtaining food for development. If the young 

 tick succeeds in lodging upon the skin of a cow, then in three or 

 four weeks ( and in cold weather much longer ) they reach their 

 full growth. The females being engorged with blood drop off 

 and begin laying eggs as did their mothers. 



Neither old nor young ticks crawl far, hence a fence with a 

 bottom rail or board on the ground will stop them, but wire 

 fences do not always afford protection. 



Ticks do not crawl from one animal to another. 



Eggs laid during the cold weather of late fall and early win- 

 ter do not hatch, hence go through the winter as eggs and hatch 

 when warm weather comes in the spring. 



All eggs laid before September ist will probably hatch the 

 same fall and, therefore, the young ticks will be killed by the cold 

 winter weather or starve to death before spring. 



Inoculation. — Not only does tick fever kill hundreds of thou- 

 sands of dollars worth of Southern cattle every year and depre- 

 ciate the value of all those marketed from one-fourth to one-half 

 cent per pound live weight, but it also offers the greatest existing 

 barrier to the improvement of the quality of Southern cattle by 

 rendering the importation of pure bred animals for breeding pur- 

 poses extra hazardous and expensive. 



For the purpose of conferring immunity on imported pure 

 bred or other cattle, a method of inoculation has been found prac- 

 ticable which reduces the loss from fifty per cent or more to ten 

 per cent or less. 



Method. — The process consists in drawing from I c. c. to 2 

 c. c. of blood from the jugular vein of an animal not less than two 

 years old that was infested with ticks the preceding summer, and 

 injecting it immediately under the skin of the animal to be inocu- 



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