22 



SCHOOL ENTOMOLOGY 



FIG. 11. The Pear-leaf Blister-mite 

 (Arachnida, Acarina). Highly mag- 

 nified. After Parrott. 



domestic animals. Ticks, which are merely large mites, 

 are external parasites on many animals. One species, the 

 Texas-fever Tick, carries the organism causing Texas fever 



in cattle from animal 

 to animal and is a 

 serious hindrance to 

 the stock-raising in- 

 dustry in the Southern 

 States. Other forms 

 transmit the Rocky 

 Mountain Spotted- 

 fever, which is a serious, and often fatal, disease of man. 

 Still others have similar and equally serious habits in 

 other parts of the world. (See page 209.) 

 Some forms of mites are beneficial 

 as parasites of injurious insects. 



Harvestmen are the long-legged forms 

 commonly known as " daddy-long-legs " 

 and found in the woods and fields all 

 FIG. 12. A Tick over the country. Their economic im- 

 (Class Arachnida, portance is extremely slight. 



Scorpions are found in the more 

 southern portions of the United States, 

 but occur as far north as northern Kansas. They have 

 the posterior part of the abdomen narrowed into a tail- 

 like appendage terminated with a sting with which they 

 can inflict more or less painful wounds. 



Other Arachnids are Pseudo-scorpions, found in moist 

 situations, frequently under bark, small in size and very 

 inconspicuous; Jointed-spiders, found only in the Southwest, 

 and a few others which are still more rare in our fauna. 



It is not advisable to take up here the further classi- 

 fication of the Arthropods, other than insects, into orders 



order Acarina). 

 Enlarged. 



