17 



nectaries are long and reach beyond the tip of the abdomen, though rarely beyond 

 the tip of the tail; they are cylindrical, tapering, becoming again slightly stouter 

 toward the end. The tail is rather long and stout, curved upward, and about two- 

 thirds the length of the nectaries, lanceolate, and more or less distinctly constricted 

 about the middle; it is densely covered with acute, minute points and furnished each 

 side of its terminal half with three, backward-curved, long bristles. The legs are 

 long and provided with short, stiff, and simple hairs. 



The color of the apterous female is yellowish-green, often slightly pruinose; fre- 

 quently darker toward the end of the body; the head varying from yellow to 

 brownish-yellow. The eyes are red to brown, while the tail varies from white to 

 a distinct yellow. The antenna?, as a rule, are black, though sometimes the first 

 joint may be yellow or the first three joints dusky. The terminal half or more of 

 the femora, apex of the tibia?, the tarsi, and the nectaries brown to black; the rest 

 of the leg is yellow. The body is frequently marked with a brownish puncture or 

 spot each side of the prothorax; sometimes there is a narrow dusky or black line, 

 composed of minute spots, each side of the mesothorax and a dorso-lateral row of 

 about five linear or rounded, blackish or dusky spots each side of the abdomen, 

 which sometimes are extremely faint or even wanting. Occasionally there are also 

 two additional small black or dusky spots between the nectaries. Lateral spots in 

 front of nectaries black. 



Winged migrant. — Expanse of wings 9 to 9.4 mm ; length of body 1.4 to 2.6 mm . 

 Antennae long, generally about one-third longer than the body; the third joint about 

 one-third shorter than the sixth and provided along its exterior or posterior edge 

 with from six to eleven more or less elevated, round sensoria along its basal third. 

 The hairs of the various joints are similar to those of the apterous female, though 

 sometimes one or the other may be distinctly clavate. TJ nectaries, tail, and legs 

 in general appearance and size are very similar to those of the apterous form. The 

 wings are almost twice the length of the body, while the venation corresponds very 

 much to that of Aphis. 



Color yellowish-green to green; the mesothorax yellow and its lobes brown to 

 black. Sometimes a small, oblique, dusky, subdorsal spot and a transverse pale- 

 dusky band may be observed on the prothorax. Head brown or brownish-yellow; 

 eyes red to brown. Antenna? black, the first joint sometimes brownish-yellow 

 externally. Nectaries black, the tail yellowish or greenish-yellow; sternal plate and 

 lateral spot in front of wings black. The abdomen is marked with four or five small, 

 transverse, blackish dorso-lateral spots and four black lateral spots in front of nec- 

 taries; the coloration of the legs is similar to that of the apterous female. Wings 

 clear, the costa dusky, and the subcosta yellow; stigma yellowish, its inner margin 

 dusky; veins yellowish-brown, changing to black toward the end. 



In order to distinguish this species, besides the niaculations of the 

 abdomen, from near related species infesting grains and grasses, I 

 have adopted the rule of measuring the comparative length of the 

 antennal joints, the nectaries, and the last fork of the wings by tenths, 

 with the accompanying result of variation: 



Joint 3, variation between 19 and 29. 

 JoimV4, variation between 13 and 20. 

 Joint 5, variation between 11 and 17. 

 Joint 6, variation between 24 and 34. 

 Nectaries, A'ariation between 11 and 16. 

 Last fork, variation between 22 and 36. 



The sexual generation or the eggs have thus far not been observed. 

 22104— No. 44—04 2 



