iQoS] Studies on Aphididae 255 



DESCRIPTIONS. 



Wingless viviparous female, stem-mother. — General appearance, to the 

 naked eye, orange. Head and thorax almost entirely bright orange. Antennaj 

 white or nearly so, excepting the tips, which are dusky. Legs concolorous with 

 antennae, excepting the tarsi, which are dark. Abdomen with two lateral, 

 longitudinal stripes of orange, the central dorsum pale greenish or yellowish 

 with longitudinal streaks of orange, the last three abdominal segments entirely 

 orange. Cornicles pale whitish, except the extreme tips. Style orange-yellow. 

 Otherwise as the wingless viviparous females of the succeeding generations, 

 excepting the measurements of the total length and width, the stem-mothers 

 usually being the greater. 



The immature stem-mothers (first and second instars) are reddish 

 brown, with dark (almost black) markings, as follows: two longitudinal rows 

 of bars along the median dorsum and only separated by a line median line of the 

 body color; and two longitudinal rows of spots, one on each of the lateral mar- 

 gins. Head very dark, with a fine median line dividing the dark area into two 

 patches. Antenna^ dusky. 



The aphids of the fourth instar of the first generation are very similar to the 

 adults in color, except that the markings are not such a bright orange and the 

 body is covered with more or less of a bloom. 



Winged viviparous female. — General body color yellow. Antennae slightly 

 dusky and faintly imbricate; not reaching beyond the bases of the cornicles; 

 segment III subequal to VI ( = VI + VII of some authors), segments IV and V 

 subequal and their combined length about equal to that of III, the basal por- 

 tion and filament of VI subequal; irregularly placed circular sensoria as follows: 

 18-24 on III, 3-7 on IV, 3-5 on V, and several at the distal end of the basal por- 

 tionof VI. (PI. XXII, fig. 15.) Eyes appearing black to the naked eye, but under 

 magnification they appear dark- or red-brov.n. Ocelli brown and distinct upon 

 the yellow back-gi-ound. Wings hyaline; the first and second discoidals branch- 

 ing at about one-third the distance from the margin to the third discoidal. 

 (PI. XXII, fig. 12.) Legs pale yellowish, except the tarsi and the distal ends of the 

 tibife, which are dusky. Abdomen a paler yellow than the head and thorax. 

 Cornicles concolorous with the body, excepting the distal ends, which are often 

 slightl}'- dusky; reaching to or slightly beyond the tip of abdomen; basal third 

 very narrow and the remaining two thirds strongly incrassate, the tips slightly 

 imbricate and flaring. Style concolorous with the body, conical, and slightly 

 more than one third the length of the cornicles. (PL XXII, fig. 13.) 



Measurements. — (Measurements from specimens motmted in balsam.) 

 Length of body, 1.40 mm.; width, 0.51 mm.; length of wing, 2.8361 mm.; width, 

 1.0544 mm.; wing expanse, 5.50 mm.; antenna, I, 0.0652; II, 0.0570; III, 

 0.3260; IV, 0.1847; V, 0.1901; VI, basal, 0.1548; VI, filament, 0.1662; total, 

 1.1440 mm.; cornicles, 0.3423 mm.; style, 0.1385 mm.; hind tarsus, 0.1141 mm. 



Wingless viviparous female. — (Summer form.) General color bright yellow 

 and often with a slight greenish tint. iVntennse whitish-yellow; the third seg- 

 ment very faintly imbricate and the remaining segments with increasing imbri- 

 cation; segment III subequal to, or slightly less than, VI (base -F filament), 

 IV and V subequal, and their combined length equal to, or slightly greater than, 

 VI.; about one-half the length of the body; the iisual sensorium near the apex 

 of V, and several at the distal end of the basal portion of VI. (PI. XXII, fig. 17.) 

 Eyes red. Legs whitish yellow. Cornicles concolorous with the body; the basal 

 third narrow and the remaining two-thirds strongly incrassate, the tip being 

 more or less flaring; reaching to or slightly beyond the end of the abdomen. 

 (PI. XXI, fig. 11.) Style concolorous with the body, conical, and between one-half 

 and one-third the length of the cornicles. 



Measurements. — (Taken from specimens mounted in balsam.) Length of 

 body, 1.5453 mm.; width, 0.7817 mm.; antenna, I, 0.0652; II, 0.0489; III, 

 0.1956; IV, 0.1304; V, 0.1355; VI, basal, 0.1110; VI, filament, 0.1418; total, 

 0.8284 mm.; cornicles, 0.3830 mm.; greatest width of cornicles, 0.0896 mm.; 

 style, 0.1548 mm.; hind tarsus, 0.1222 mm. 



