26 CLASS ARACHNIDA 



are fitted for piercing, biting, or in some cases for combined 

 biting and suction, there being usually a pair of slender, 

 sharp mandibles capable of penetrating the skin of the 

 host animals. Much variation of habit exists, and ranges 

 from free forms to strictly parasitic forms. 



Fig. 5 — Tetranychus gloveri: Adult — much enlarged, (Titus, Div. 

 Ent., U. S. Dept. Ag.) 



Harvest Mites; Chiggers. 



In the family Tromhidiidoe, which includes normally plant- 

 feeding species, we find a few species which have adopted 

 a phase of parasitism which, though apparently abnormal, 

 results in extreme annoyance to the animals affected. 



Apparently the most abundant species in this country 

 is the Leptus irritans of liiley, which is illustrated herewith. 

 This occurs in a large portion of the United States, and 

 occasions during the summer months an enormous amount 

 of suffering. It ranges north in the INIississippi Valley into 



