104 
The winged viviparous female (PI. III., Fig. 6) has a row of ten 
to twelve sensoria on the third antennal segment. Wings hyaline ; 
veins dark brown to black, narrowly bordered with brownish, with a 
small brown patch at the outer end of each vein ; basal half of stigmal 
vein obsolescent; discoidals as in the figure. The abdominal tuber- 
cles of the two inner rows are oblong, and each of them bears two fine 
setae. The remaining tubercles, more or less circular, have each but 
one seta. Average length, 1.4 mm. 
The wingless oviparous female is at first pale yellow, but the ab- 
domen (excepting the last two segments) becomes progressively 
orange as the eggs develop in the body, and the orange color may 
eventually extend over most of the thorax. Eyes black. The anten- 
nae do not reach to the cornicles, and the third antennal segment has. 
eight or ten circular sensoria. Hind tibiae swollen, and with sensoria. 
Dorsal abdominal tubercles essentially as in the winged viviparous 
female. Average length, 1.8 mm. 
In the zvitiged male the head and thorax are pale olivaceous 
green, and the, abdomen pale yellowish green, with conspicuous black 
dorsal spots. Antennae black (excepting the first two segments) and 
as long as the body, with sensoria as follows: 12-15 on segment 
three ; 2-4 on four ; 3-5 on five. Wings essentially as in the female. 
The large black oval setiferous spots of the abdomen fall chiefly into 
four rows — two dorsal and two lateral, with scattered spots between 
the former and the latter, on each side. Style and cornicles dusky. 
Average length, 1.2 mm. 
The absolute lengths of the segments of the antennas and legs, as 
well as those of the cornicles, are, as in other aphids, too variable to 
be of much importance as specific characters. The relative lengths 
are more constant, however, and hence more important for the sys- 
tematist. They appear from the following table, which consists of the 
averages of many measurements made from Urbana specimens by J. J. 
Davis and from types of Mr. Monell — made by himself. 
C. trifolti 
Antennae 
Style 
Cor- 
I 
II 
III IV V i VI 
nicles 
Wingless viviparous female 
Winged viviparous female 
Winged viviparous female, 
Monell's types 
Wingless oviparous female 
Winged male 
07 mm. 
()7 
.05 
.07 
(K) 
.05 
.05 
.04 
.05 
.05 
.51 .i4 .31 .15+. 16 
.51 .36 32 .16-1-16 
.44 31 .28 .15+. 13 
.40 .19 .20 .13-I-.14 
.51 30 1 .29 .15-h 15 
.17 
.13 
.06 
.06 
.06 
.04 
The egg. hitherto undescribed, is much like that of any other 
aphid in being elliptical, 0.57 mm. long, and 0.25 mm. broad, but has a 
characteristic bright orange-color when recently laid. 
