38o 



COLLEGE ZOOLOGY 



The family Trombidiid^e includes the harvest mites or 

 " chiggers " (Fig. 321). These little creatures are transferred 

 by contact from plants to the bodies of man and other animals. 



They burrow into the skin, 

 ^ with painful results. 



Treatment with a one or 

 two per cent solution of 

 carbolic acid is the proper 

 remedy. The poultry 

 tick, Dermanyssus gallince 

 (Fig. 322, A) belongs to 

 the family Gamasid^e. It 

 sucks the blood of chickens, 

 and is a pest on poultry 

 farms. 

 The family Ixodid.e contains a number of injurious species. 

 The cattle tick, Boophilns {Mar gar opus) annul atus (Fig. 322, B), 

 is perhaps the most important. These ticks cling to the skin of 

 cattle with their strong mouth-parts, and suck the blood of their 

 host. When full grown the females drop to the ground and lay 

 from 2000 to 4000 eggs; these soon hatch, and the young crawl 

 upon a blade of grass and wait for cattle to come past to which 

 they can fasten themselves. The principal injury done by the 



Fig. 321. — Order Acarina. Harvest- 

 mites or " chiggers." Leplus irr'Uans on 

 the right; L. americana on the left. (From 

 Osborn, after Riley.) 



Fig. 322. — Order Acarina. A, poultry tick, Dermanyssus gallince, young, 

 B, cattle tick, Boophilus annulatus. 



