26o Annals Entomological Society of America [Vol. I^ 



clover aphis. I accordingly sent Professor Gillette specimens, 

 in regard to which he reported that they "seem to be identical 

 with what we have been calling Aphis bakeri. A. bakeri is not 

 a subterranean species, but it does w^ork close about the bases of 

 the plants, particularly during the colder portions of the year." 

 He also stated that A. cephalicola Cow. was now considered a 

 synonym of A. bakeri, and further that he had collected it on 

 apple and Crataegus as well as on clover. 



Last summer (1907) I received specimens of a clover aphis 

 from Mr. Paul Hayhurst, which I determined as A. cephalicola, 

 not knowing at the time that it was a synonym of A. bakeri. 

 These specimens were collected in Minnesota and Mr. Hayhurst 

 has written that he has also taken this species in Kansas and the 

 District of Columbia. 



I have used the name of A. bakeri as having priority, inasmuch 

 as the incomplete description of A. trifolii was made from imma- 

 ture individuals only, and we can not be certain that this is the 

 same species; although the pinkish coloration of some of the 

 immature individuals, as well as pseudo-subterranean habit, 

 suggests that they are what was described as A. trifolii. 



DESCRIPTIONS. 



Winged viviparous female. — General color black. Head jet black. (PI. 

 Ill, fig. 23.) Antenna; black, not reaching the cornicles, and with numerous 

 unequal tuberculate sensoria, irregularly placed on segments III, IV, and V, as 

 follows: 22-33 on III, 2-18 on IV and 1-11 on V (usually, however, but the 

 one large distal sensorium on V), also several smaller ones at the distal end of 

 the thickened base of VI; segment III usually the longest, but occasionally it is 

 subequal to VI ( = VI and VII of some authors), IV slightly shorter than the 

 filament of VI, V about half the length of III, and the basal portion of VI about 

 half the length of IV. (PI. XXIII, fig. 24.) Eyes black. Beak not reaching 

 beyond the coxce of the middle pair of legs. Thorax jet black. Wings hyaline 

 and with dark veins; the first and second discoidal usually branching at one 

 half the distance from the margin to the third discoidal, this, however, is more 

 or less variable, the distance sometimes being greater, and sometimes less, than 

 one half. (PI. XXIII, fig. 22.) Legs almost entirely black. Abdomen more or 

 less glossy and appearing black to the naked eye. Magnification shows a large, 

 black patch covering most of the dorsum, and two rows of small black spots 

 along the margin, one on each side; the remainder of the dorsum having a green- 

 ish tint. The black patch is solid, except one bar anteriorly, and several pos- 

 teriorly, to it. (Sometimes the dorsal patch, instead of being almost an entire 

 mass, is made up entirely of individual transverse bars.) Cornicles black, imbri- 

 cated, and more or less flaring at the apex. (PI. XXIII, fig. 26.) Style black, 

 and conical. (PI. XXIII, fig. 27.) 



Measurements. — (Many specimens were measured, and the maximum and 

 minimum, as well as the averages, are given. There is considerable variation 

 in the actual measurements of the antennal segments, length of body, etc., 

 between difl^erent individuals, but the relative lengths of the antennal segments, 

 length of body, etc., are c^uite constant.) Length of body, 1.2726-1.8543, 

 average, 1.4857 mm.; width, 0.6181-0.7979, average, 0.6825 mm.; length of 

 wing, (average) 2.39 mm.; width, 0.88 mm.; antenna, I, 0.0682; II, 0.0565; III,. 



