THE AGAR IX A OR MITES— BANKS. 



23 



Family TETRANYCHID.E. 



The members of this family, commonly known as "red spiders," 

 have for many years attracted attention, owino- to their ravag-es to 

 cultivated plants. Since many of the species can spin a silken thread, 

 they have also been called "spinning mites." Their structure presents 

 few remarkalile characters. The body is 

 oval or elliptical, provided with a few, 

 mostly long-, hairs, arranged in four rows. 

 The cephalothorax is separated from the 

 abdomen by a furrow, and bears on each 

 •side one or two simple eyes. The palpi 

 are short, the penultimate joint ending in 

 a claw. The last is ''thumb-like" and 

 bears one or more appendages called 

 "•lingers." In some species the palpus of 

 the male has a short curved spine at the 

 tip on the upper side of the third joint. 

 The mandibles have their basal joints 

 united in a plate; the apical joint, being 

 very long and flexible, is fitted for pierc- 

 ing- plant tissues, and is known as the 

 stylet. The legs are moderately slender, 

 the tirst pair the longest, with scattered 

 hairs, and ending in one or two claws. 

 In many species of Tetranyelum the claw 

 is split into four pieces, whence the name. 

 On the under side of the abdomen are two 

 simple openings, the basal the genital, the other the anal. The former 

 in the female is usually transverse. In the male it is longitudinal and 

 often shows the slender curved penis. 



The genera recognized in our countr}^ may l)e separated as follows: 



1. Front margin of cephalothorax with four scale-Hke projections, l)ody with scale- 



like hairs above; leg I longer than Ijody Bryohki. 



Xo scale-like projections on front of ce])hal()thorax 2. 



2. All the legs much longer than body, which is short and broad; rostrum not prom- 



inent from above NeophyUohius 



Few of the legs but little longer than body 3. 



'?>. Pah^i ending in a distinct "thumb;" not very slender 5. 



Palpi not ending in a distinct "thuml)" 4. 



4. Palpi very small and slender; legs short and heavy, usually rugose; eyes distinct 



TeniiipaJpus. 



Palpi of moderate size, legs longer, not rugose; eyes indistinct or absent 



Tetranychoidei<. 



5. Body twice as long as broad; legs very short Stlgnncus. 



Body one and one-half times as long as broad; leg I longer than 1)ody 



Tetranychus. 



Fi<;. 'iri. — Tetranychus BiMAfTLAXfs. 



