No. 2303. RED SPIDERS OF AMERICA— McGREGOR. 651 



has long been recognized as an economically important species, and 

 has been treated taxonomicall}^ and economically by many workers 

 since Linnaeus, including Boisduval, Lucas, Wliitehead, Murray, 

 Ormerod, Oudemans, Berlese, Canestrini, Fanzago, Von Hanstein, 

 Tullgren, Noel, Bruyant, Keifi'er, Tragardh, Banks, and Ewing. 



Among American workers Ev/ing (17) alone lias claimed that the 

 common red spider described in 1892 by Harvey as T. himamlatus is 

 identical ^Aith the linden mite. He claims also that T. sexmaculatus 

 Riley and T. gloveri Banks are synonyms of T. telarius. The present 

 writer believes he has established in the present work the valid 

 specific distinction of each of these excepting T. glm^eri, which he 

 finds to be identical with T. himaculatus. 



The linden mite of Europe is the smallest of the true Tetranychus 

 species. It feeds commonly on linden, elm, horse-chestnut, maple, 

 aspen, and bird-cheny. In Europe T. telarius is laio"wai to occur in 

 England, France, Germany, Norway, Sweden, Denmark, and Italy. 

 American material has been determined at times by Banks as T. tela- 

 rius, but the latter authorit}" admits that he has not given the matter 

 the critical analysis that present-day workers in the Tetranychidae 

 have found to be necessary for the proper separation of species. The 

 present author has never collected the linden mite in this country. 



The description of the European T. telarius as compiled from ac- 

 counts by European workers is as follows: 



Ijength of female, 0.42 ram.: length of male. 0.33 mm. Color yellowish-gi'eenish- 

 yellow, sometimes green and with the hibernating females orange-yellow. A single 

 eye cornea on each side. The body has the typical 

 13 pairB of bristles, of which those located in the hind 

 half of the hysterosoma are the shortest ; bristles not 

 at all pilose: the two front vertex hairs are shorter 

 than the hind ones; the hairs are fine, the longest 

 of them being about one-third the length of the body. 

 The collar trachea is V or U shaped and of about even 

 thickness throughout. A trans vei'se suture sharply 

 separates the proterosoma from the hysterosoma, and 

 immediately behind tliis line the body attains its 

 greatest width. Leg I of male has empodiu.m of same 

 structure as the other pairs of lege. Empodial claw 

 sometimt-s t)-cleft, but usually 4-cloft . Penis slender, y^^^ ;5— Tetr vnychcs tel\riu3 

 the inner lobe rod-like; the basilar lobe obtusely Linnaeus, i, tarsal append- 

 sharp angled; the shaft somewhat thicker than inner ages; 2,collar trachea; 3, palpus 



AND IT.S 

 GlTtDH). 



lobe and is bent upward about G0° from the shaft ^^'^'"'^ appendages (after TrX. 



axis to form the hook, which is acuminate pointed. 

 Palpal ' ■ thumb '" with stout terminal ' " finger. ' ' which at base is nearly as wide as tip 

 of "thumb:'" a pair of digituli at upper distal angle; a small dorsal "finger" midway 

 to base than which the terminal ""finger " is two and one-half times as thick, a pair of 

 shon hairs between dorsal "finger" and base: and a hair arising latero-ventrally from 

 the middle of the "thumb." Hook of the penidtiaiate joint just reaching to the 

 dorwal "finger." 



