THE RELATIONS OF ARACHNIDS TO MAN 



125 



of a brownish or bluish-black color. Since they are principally 

 active at night, the fowls may escape them by resting on perches 

 hung from the ceiling with wires or iron rods. 



Mites which Cause Scab and Mange. — Certain mites (Fig. 

 69, C) cause diseases known as scab or mange on sheep, horses, 

 dogs, and other animals. The sheep scab mite is the most im- 

 portant and must be fought instantly wherever sheep are reared. 

 The scabs are caused by the working of the mites in the skin 



Fig. 70. — A sheep injured by the scab mite. (From Farmers' Bulletin.) 



(Fig. 70). These mites may be killed by dipping the sheep in 

 the same manner as that suggested for eradicating the sheep 

 tick (see p. 54). 



Itch Mite. — The mites that attack man are comparatively 

 unimportant. The itch mite (Fig. 71, B ) is very closely related 

 to the sheep scab mite. It is a minute, whitish mite which lives 

 in the skin and causes intense itching. Cleanliness will prevent 

 infection, and sulphur ointment will eradicate the ticks. 



Harvest Mites or Chiggers. — The harvest mites or chiggers 

 (Fig. 71, A) lie in wait in the grass or on shrubs until some luck- 



