82 



ANIMAL BIOLOGY 



very quiet way of boring their head into one's skin, and 

 they are frequently not discovered until they have so 

 gorged themselves with blood that they are many times 

 their original size. After a full meal they may live 

 considerably over a year without food. Ticks, like 

 mosquitoes, are the means of spreading disease. Texas 

 fever which sometimes exterminates many thousands 

 of cattle is carried from one animal to another by ticks. 

 Rocky Mountain fever, a disease of man prevailing in 

 certain parts of the west, is also carried by ticks. A knowl- 



FIG. 68. FIG. 69. 



FIG. 68. Tick that produces the Rocky Mountain fever. (After 



Hunter and Bishopp.) 



FIG. 69. Female of Texas fever tick laying eggs. (After Hunter and 



Bishopp.) 



edge of the mischievous role of ticks has resulted in 

 greatly checking the spread of both these diseases. 



The mites form a very large group of usually very small 

 creatures. Some live in water, others in damp soil, others 

 on plants, others attack animals. The chicken mite 

 which causes so much discomfort to our poultry, is a com- 

 mon pest. The small cheese mites are a frequent nuisance, 

 but perhaps the most acutely disagreeable of all are the 



