igoS] Studies on Aphididae 257 



Missouri, and Doctor J. W. Folsom found it on clover in New 

 York, July 22, 1908. 



Heretofore it has been stated that individuals of the genus 

 Callipterus always become winged before reproducing vivipar- 

 ously. This characteristic does not always hold true for C. tri- 

 folii, for I have found wingless individuals giving birth to young. 

 As a rule, however, most of the young are produced by winged 

 individuals. 



DESCRIPTIONS. 



Wingless viviparous female. — General color of body pale green with a faint 

 yellowish tint, and with dusky tubercular spots on the dorsimi. Antennae pale 

 whitish green at base, but becoming dusky and black towards the apex; very 

 faintly imbricate, as long as, or slightly longer than, body, 9-12 sensoria in a 

 row on segment III. (PI. XXIII, fig. 30.) Eyes dark red. Beak not reaching 

 beyond the coxae of the second pair of legs. Legs pale, excepting the joints, 

 which are dusky, and the tarsi, which are black. The six longitudinal rows of 

 tubercles as in winged form, excepting that they are more prominent and bear 

 conspicuous capitate hairs. Cornicles and style as in winged individual. 



Measurements. — (From specimens in balsam, collected on Trifolium pra- 

 tense at Urbana, 111., September 4, 1907.) Length of body, 1.49-1.67, average 

 1.60 mm.; width, 0.72-0.83, average, 0.76 mm.; antenna I, 0.076; II, 0.053; 

 III, 0.489-0.554, average, 0.517; IV, 0.326-0.375, average, 0.347; V, 0.285-0.342, 

 average, 0.316; VI, basal, 0.146-0.163, average, 0.156; VI, filament, 0.155-0.179, 

 average, 0.162; total (average) 1.627 mm.; cornicles, 0.062 mm.; style, 0.171 mm. 

 hind tarsus, 0.130 mm. 



Winged viviparous female. — General color pale yellowish green, with dusky 

 markings on the dorsum. Antennae concolorous at Isase and darkening towards 

 apex, longer than body, with 10-12 sensoria in a row on segment III, and faintly 

 imbricate. (PI. XXIII, fig. 29.) Eyes dark red to brown. Beak not reaching to 

 coxae of second pair of legs. Wings hyaline; veins dark brown to black, with a 

 very narrow border of brownish tint and with a small brown patch at apices of 

 veins, basal half of stigmal vein obsolescent, terminal forks of discoidal branch- 

 ing at a point slightly less than one half the distance from where the discoidal 

 first branches. (PI. XXII, fig. 20.) Legs concolorous with body, excepting tarsi, 

 which are nearly black. Abdomen with six longitudinal rows of dusky tubercles, 

 three rows on each side of the dorsal median The tubercles of the two rows on 

 each side of the median are oblong, and each tubercle bears two fine setae. The 

 other tubercles are more or less circular, and each bears but one seta?. Cornicles 

 (PL XXII, fig. 1) and style (PI. XXII, fig. 21) somewhat dusky, the former tuber- 

 cular and the latter globular. 



Measurements. — (From specimens in balsam, collected on Trifolium pra- 

 tense at Urbana, 111., August 25 and September 4, 1907.) Length of body, 1.345- 

 1.564, average, 1.454 mm.; width, 0.582-0.691, average, 0.642 mm.; expanse of 

 wings, 4.654 mm.; length of wing, 2.045 mm.; antenna, I, 0.077; II, 0.055; III, 

 0.489-0.538, average, 0.516; IV, 0.358-0.391, average, 0.368; V, 0.301-0.358, 

 average, 0.320; VI, basal, 0.146-0.179, average, 0.167; VI, filament, 0.146-0.179, 

 average, 0.162; total (average), 1.665 mm.; cornicles, 0.066 inm.; style, 0.139 

 mm.; hind tarsus, 0.129 mm. 



The following table gives comparisons of the average lengths 

 (in millimeters) of the antennal segments of the type specimens, 

 specimens from Mr. Hayhurst and the Illinois specimens. The 

 measurements of the type specimens and of those' collected by 

 Mr. Hayhurst were made by Mr. Monell, who has kindly sent them 

 for my use. 



