1909] Studies on Aphididae II 35 



slightly less tlian VI and about a third greater than IV ; IV and V subequal ; basal 

 VI less than V and greater than filament VI. Eyes red. Beak not reaching or 

 barely reaching the cox;e of the second pair of legs. Prothoracic segment 

 brownish to black, with a small yellowish ai-ea on each side of the median, 

 and often with a threadlike pale median line. The coloration of therneso- and 

 the meta-thorax the same as that of the abdomen described below. The two 

 fore pairs of legs pale yellowish, excepting the dusky distal end of the tibiae 

 and the black tarsi; hind pair with the tibiae, and distal halves of the femora 

 dusky to black, and the tarsi black; hind tibiae swollen and bearing about 35 

 irregularly placed, inconspicuous, circular sensoria on the basal halves. (PI. V, 

 tig. 15.) The two posterior thoracic and the abdominal segments with a black 

 transverse band on each side of the median line, and a black spot on each side; 

 the interspaces yellow. The anterior dorsal bands necessarily shorter and the 

 bands on segments 5, 6 and 7 uniting in the middle, thus forming a single trans- 

 verse band on each of these segments. The position of the dorsal markings is 

 well illustrated by Koch in "Die Pflanzenlause," figure 283. Cornicles blackish 

 and tuberculate as those of the viviparous female. Style pale yellowish. At 

 base of each cornicle and beneath the body, on each side, is a very noticeable 

 silvery white spot, which disappears on specimens mounted in balsam, the same 

 arete on the undersides of such specimens being represented by a brownish spot. 

 Measurements [from 8 specimens mounted in balsam] : — Length of body, 

 2:00 mm.; width, 0.89 mm.; antenna, I, 0.08; II, 0.065; III, 0.41-0.50, av., 

 0.44; IV, 0.23-0.30, av., 0.27; V, 0.24-0,30, av., 0.275; VI, base, 0.17-0.23, av. 

 0.20; VI, filament, 0.14-0.185, av. 0.165; average total, 1.495 mm.; style, 0.145 

 mm.; hind tarsus, 0.15 mm. 



Winged niale : — The male may readily be distinguished from the winged 

 viviparous female by its smaller size and by the sensoria on the antennae. The 

 antennas of the female bear sensoria only on the basal halves of III, and the usual 

 ones at the distal ends of V and base VI, while the male antennte bear them on 

 every segment excepting I and II. (Described from specimens collected at 

 Chicago, 111., September 15 and October 8, 1908.) Head usually dark brownish 

 to blackish excepting a more or less triangular yellowish area at the posterior 

 portion; sometimes, however, the yellowish area extends to the fore border of 

 head. Antennas black excepting the pale dusky filament of VI and the extreme 

 base of all segments beyond III; annulations as on the antennas of the winged 

 viviparous female; total length a little more than that of the body, III the long- 

 est, and slightly less than twice IV, IV and V subequal, VI about two thirds III, 

 and the base VI longer than the filament; 30 to 38 transverse sensoria placed 

 more or less in a row^ the entire length of III, 6 to 9 on IV, 7 to 9 on V, 3 to 5 on 

 base of VI, and the usual one at distal end of the same. (PI. V, fig. 16.) Eyes 

 red. Beak not reaching the base of the coxae of the second pair of legs. Pro- 

 thorax yellowish with the typical black lateral stripe which extends from the 

 eyes to the base of the wings. Thoracic shield brownish to blackish. Wings as 

 those of the viviparous female, except that they are smaller. Fore pair of legs 

 yellowish or slightly dusky, with the tarsi black, hind pair with the femora, 

 bases of tibite, and tarsi blackish, and the middle pair usually intermediate 

 between these two types of coloration; the middle and hind femora usually with 

 the clear circular arete referred to in the description of the viviparous fernale. 

 Abdomen pale yellowish green, with a row of short, transverse, blackish mark- 

 ings on either side of the median dorsal line, and a partial row of dots on each 

 side. Cornicles dusky and tuberculate as in the other forms. vStyle yellowish 

 or with a slight duskiness. 



Measurements [taken from six specimens mounted in balsam] : — Length of 

 body, 1.42 mm. ; width, 0.56 mm. ; length of wing, 2.41 mm. ; width, 0.87 mm. ; 

 expanse, approx., 5.50 inm. ; antenna, I, 0.08; II, 0.065; III, 0,60-0.66, av. 

 0.63; IV, 0.34-0.37, av. 0.36; V, 0.32-0.39, av. 0.35; VI, base, 0.21-0.26, av. 

 0.23; VI, filament, 0.14-0.21, av. 0.17; average total, 1.885 mm.; cornicles, 0.05 

 mm. ; style, 0.10 mm. ; hind tarsus, 0.13 mm. 



