38 



KEPOET 108, U. S. DEPARTMENT OF AGEICULTUEE. 



iiig it down upon the mites. One application is usually sufficient. Berlese has pro- 

 posed Eustigmaeus for species of Stigmaeus with short al)domen and Macrostigmams 

 for those with slender subcylindric abdomen. These species have been taken in moss. 

 The species of Tetranohia and Tetranychina have slender 

 legs, the first and last pairs usually longer than the body; 

 they occur on plants after the manner of Bryohia and are 

 sometimes injurious. The few forms known occur in the 

 southern or western parts of our country. Stigmaeopsis 

 celarius Banks is similar to Tetranychus in appearance; it 

 makes small white webs on bamboo; the mites live under 

 the webs; it now occurs in Florida and California. 



Caligonus (redescribed as Eupalopsis) differs from -S^(^- 

 maeus in having the thumb to the palpus very slender and 

 reaching much beyond the end of the claw. 



Tetranychoides is based upon one species, T. califomica 



Banks (fig. 49), which occurs in small colonies on the leaves 



of orange. Each colony is usually in a slight depression 



FIG. b2.-Tennipalpus caiifor- """^^ '' evident to the naked eye as a snow-white patch, this 



nicus. (Author's iliustra- appearance being due to the fact that the molted skins are 



*^°^-> retained attached to the leaf. The mites, which are almost 



colorless, and their eggs are located among these molted skins. Thevarenot as yet 



numerous enough to do any appreciable damage. 



Ewing has described a species of Stigmaeodes from Iowa; it differs little from Stig- 

 maeus, the body being more slender and with several hairs between the claws. 



Trag^rdh has described a genus, Pimeliaphilus, from Egypt, near Acheles; the cox£e 

 appear to be separated in groups and the palpus has a distinct thumb. The female 

 has a small anterior shield and other small 

 shields at base of the dorsal bristles. The tarsi 

 have two simple claws; otherwise it is a Tetrany- 

 chus. The same author describes a form from 

 Egypt as Phytotipalpus. Its general structure 

 is similar to Tenuipalpus; it lives in small galls 

 on the bark of acacia trees, and Trag^rdh has 

 traced its development, which presents nothing 

 unusual. 



Red-spider damage ia common in nearly all 

 foreign countries, but the generic positions of 

 the mites that cause it are not easily discernible 

 from the meager descriptions. In India and 

 Ceylon one species, called Tetranychus bioculatv^ 

 Green is a very serious pest to the tea plant. 



Family ERYTHR^ID^. 



These common mites are similar in many ways 

 to the harvest-mites (Troml)idiida') and l)y many 

 authors have been united to them. They are 

 nuich like Trombidiumin appearance, but nearly 

 all are of more slender proportions and more rapid 

 in motion. The body is usually divided, al- 

 though not so plainly as in the Trombidiidtc, into 



two parts. The cephalothorax is quite large and on the same plane as the abdomen 

 Along the middle of the cephalothorax is a line or furrow, known as the dorsiil groove 

 or crista. It is usually enlarged at the i)osterior end, sometimes in the middle and 



Fig. as.— Ncophijllobius amcricanus and 

 tarsal claw. (Author's illustration.) 



