660 PROCEEDING'S OF THE XATlUXAL MUSEUM. vol.56. 



shaped, anterior arm slender, expanding and bending upward and backward into the 

 short, conical pcsterior arm. Penis [see pi. 79, fig. 5] with slender inner arm, basilar 

 lobe merely an obtuse prominence, shaft very similar in size and outline to inner 

 lobe, tip obliquely truncate and produced ventrally into a very inconspicuous spur. 

 Relative lengths of joints of foreleg as follows: Ooxa 20, trochanter 9, femur 23. patella 

 12, tibia 13, tarsus 16 (see pi. 78). 



This mite has done much to injure the citrus trees in Florida since 

 1886, according to Riley. Mr. W. W. Yothers tells me that the 

 6-spotted mite is most abundant in Florida during February and 

 March. The species works in restricted colonies, causing severe yel- 

 low blistering of the leaf. When abundant, as is frequently the case, 

 an alarming amount of defoliation of the citrus trees occiu-s. 



TETRANYCHUS WELDONI Ewing. 



Plate 79, fig. 6. 

 Tetrani/chus lueldoai Ewing, 1913, Ann. Entom. Soc. Amer., vol. 6, p. 457. 

 Ewing (15), in his original descriptioj\ of this species, says that for 

 a long time he had confused this mite with T. Umaculatus, but that 

 he had demonstrated that the males of the two species are quite dis- 

 tinct. Swing's description of the species follows: 



Female: Similar in all respects to the female of T. telarius Linn. 



Male: Different from male of T. telarius Linn, in characters of penis and spur on 

 palpus. Spur on palpus not so pointed as in T. telarius Linn. Penis very long, rod- 

 like, equal to one-tliird the length of the body. Inner lobe short, rod-like, slightly 

 swollen at its anterior end. Shaft rod-like, not setiform; gradually tapering as you 

 pass backward; posterior one-half turned upward; tip narrowly rounded, not pointed. 

 Basilar lobe absent. Hook absent. Barb absent. (See pi. 79, fig. 6.) 



From Grand Junction, Colorado; on apple, prune, cottonwood. 



TETRANYCHUS WILLAMETTE! McGregor. 



Plate 79, fig. 1. 

 Tetranychus tviUametUi McGregor, 1917, Proc. U. S. Nat. Mus., vol. 51, no. 

 2167, p. 586. 

 Color, pale lemon-yellow. Eyes single on each side. Legs and 

 palpi, pale color. Dorsal bristles not arising from tubercles. Body 

 of female elliptical, four-fifths agahi as long as broad, widest between 

 legs III; length, 0.25 mm.; breadth, 0.14 mm. Bristles, about 22, in 

 four dorsal rows, the longest about half the width of body. Man- 

 dibular plate with parallel sides, two and three-quarter times as long 

 as broad, rounded at tip with no emargination visible. "Thumb" 

 of palpus of very unusual form— semispherical or subconical, bear- 

 ing at its tip a very slender, long "finger" ; on its upper side near apex 

 are two pin-shaped pseudo-fingers, and on same side about midway 

 to base is a "finger" shorter and even thinner than terminal "finger" ; 

 between this and base are two slender haus a trifle longer than sub- 

 basal "finger" ; a slender hair arises latero-ventrally one-third the dis- 

 tance from tip to base of "thumb." The claw on the penultimate 

 joint does not reach to subbasal "finger." The legs are rather short; 



