The Aphididae of Nebraska \J 



normally curved ; cubital vein obsolete for nearly one third its length, the 

 f ureal forming with it almost a point ; the terminal distance between first 

 and second discoidals equal to about five times that between their bases 

 (often rather more) ; terminal distance between furcal and cubital and 

 cubital and second discoidal veins subequal, that between stigmal and furcal 

 slightly shorter, that between second and first discoidals one third greater, 

 and about equal that between stigmal and stigma. Hind wings with the 

 subcostal almost straight, there being a curve where it gives off the dis- 

 coidal veins, which are obsolete at their extreme base and not confluent 

 with it. (The wing venation is very constant. Out of nearly ioo speci- 

 mens examined, I have found only an unusual shortening of the cubital 

 in two individuals.) The larva and pupa in this third generation differ 

 from the winged insect in being more reddish and having the antennae 

 ringed with less distinct constrictions, in the legs being paler, in the claws 

 being stronger and in the basal joint of the tarsus being more connate with 

 the terminal joint. They have a distinct annulated elevation at each side 

 posteriorly — a sort of pseudo-honey tube. When first born, they are of a 

 dull yellow, and the antennal joints are more than equal in length. 



" Fourth generation : That from the first winged females : Differs from 

 the preceding in the promiscus being much longer, in the antennae having 

 but five joints, the third being somewhat longest and the first the shortest, 

 but all often being much more nearly equal in length, with no annulated 

 constrictions. The color is more decidedly orange. When newly hatched, 

 the thickened end of the promiscus often extends half the length of the 

 body beyond the anus. The legs are long and stout, and the basal joint 

 of the tarsus is distinct, but not separated. The capitate hairs are obso- 

 lete. It is born with an enveloping pellicle or pseudovum, and though of 

 a bright red with pale legs at first, soon becomes brownish, with dark 

 members. 



" Fifth generation : The counterpart of the second. 



" Sixth generation : Second winged : Resembles the third, but usually 

 rather lighter colored, with the wing-veins, the spinous armature of sur- 

 faces and the constrictions of the antennae less strong, and with the third 

 joint of antennae rather less in length than the terminal three together. 



" Seventh generation : True sexual individuals : Born within an egg-like 

 pellicle. With stout promiscus reaching beyond the middle coxae; the 

 antennae 5-jointed, with the joints subequal. Bark-feeding. Orange in 

 color. Undergoing one molt and then being at once distinguished from 

 the other forms by the brighter orange yellow color, the rudimentary 

 mouth, the more simple eyes (composed of three facets), by the shorter 

 5-jointed antennae, the joints subequal in length; by the shorter legs, with 

 smaller claws to the tarsi, and more distinct terminal capitate hairs, or 

 pulvilli. The skin is transparent, the body filled more or less with fatty 

 globules. The female is nearly pyriform, and averages 0.40 mm. in length. 



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