654 PROCEEDINGS OF THE AAIIuNaL MUSEUM. vol.56. 



Ewing (15) writes that this species is a serious pest to apples in the 

 Hood River Valley and the Willamette Valley, Oregon, and that it 

 probably occurs throughout tlie Pacific Northwest above altitudes 

 of 1,000 feet. He adds that "when fall comes and the trees drop 

 their leaves, these mites all become a pale yellow in color, and collect 

 in masses about the trunks of trees and the cracks of the ground for a 

 region of several feet from the tree bases. Here they pass the winter, 

 and become active again in the spring, when the trees put out their 

 foliage." 



TKTRANYCHUS MULTIDIGITULI Ewing. 



Tetramjchus nmllvJigituli. Ewing, 1917, Jouni. Econ. Ent., aoI. 10, Octolr-rT, 

 p. 497. 



Swing's (22) original description of this species is as follows: 



Preserved specimens yellowish. Body somewhat depressed, 

 skin more or less wrinkled, and abdomen somewhat pointed 

 behind. Palpi prominent; claw strong and much curved; 

 "thumb" stout, almost as broad as long, and not sur- 

 passing the claw; digit of "finger" about half as long as 

 "thumb" and less than half as long as broad; digituli or 

 spines, at least five near tip of "thumb," setae also present 

 on 'thumb."' Mandibles or chelicerae, slender, with a simple 

 loop toward base, and of uniform diameter except at base 

 where they are slightly swollen. A single pair of eyes pres- 

 ent, placed laterally; cornea strongly curved. Abdomen 

 Fig. 4.— Tktranychus clothed above with rather stout, simple, slightly curved setae. 



MULTiDioiTULi Ewing. Legs moderate; tarsus of leg 1 about one and one-third times 



Palpal appendages f ., . , . . 



(AFTEii Ewing ~). '^^ '*^^o ^^ tibia, and truncate at its tip, from which springs a 



veri' long tactile seta. Tarsal claws rather weak, strongly 

 curved near their bases, beyond which they are divided into six prongs. Onychium 

 with four tenent hairs. Length, 0.30 mm.; width, 0.21 mm. 



According to Ewing this species is described from several speci- 

 mens on the bark of honey locust (Gleditsia triacantlws), collected by 

 J. S. Houser. The author states that the "species differs from most 

 of the other species in the genus in having several digituli, or setae, 

 near the tip of 'thumb;' in having the setae of the body relatively 

 short and of about the same length, and in having the tip of the 

 tarsus broad and truncate." 



TETRANYCHUS BIMACULATUS Harvey. 



Plates 76, 79, fig. 11, and plates 80 and 81. 



Tetramjchus bimacufotuH Harvey. 1892(1S93\ Ann. Rept. Maine Agric. Exp., 



Sta., p. 133. 

 fTetranychus vitis Boisduval, 1867, Entom. Horticole, p. 92. 

 Tetramjchus desertorum Banks, 1900, Tech. Bull. No. 8, Div. of Ent.. U. S. 



Dept. of Agric, p. 76. 

 Tetramjchus verbesinae Cockerell, 1902, Nature, vol. 16, Oct., p. 608. 

 Tetranychus gloveri Banks, 1900, Tech. Bull. No. 8, Div. Ent., U. S. Dept. 



Agric, p. 76. 

 Tetranychus opuntiae Banks, 1908, Proc. Wash. Ent. Soc, vol. 10, p. 36. 



