6 BULLETIN 826, TL S. DEPARTMENT OF AGRICULTURE. 



degenerate, beakless, nonfeeding individual of the Eriosoniatinae, but 

 feeds upon the leaf like the viviparous forms. Moreover, in external 

 structure these insects resemble certain ones of the Callipterini, to 

 such an extent, indeed, that Davidson has described one of these 

 forms as a Chaitophorus. Certain of the structures met with in these 

 forms resemble those found in the Hormaphidinae and on these 

 structures the tribe might be placed there. The writer believes, 

 however, that the true affinities of the tribe are shown by comparison 

 with the Phyllaphidina. It will be seen at a glance that there is a 

 very close resemblance in all main characters. But the sexual forms 

 are different, although not so strikingly different as would appear at 

 first. In the Phyllaphidina both winged and wingless ovipara and 

 as a rule winged males occur. But in some species (quercifoliae) 

 intermediate and apterous males also occur. It is not a very long 

 call, therefore, from the apterous males and females of the Phyl- 

 laphidina to the apterous sexes of the Thelaxini. But the habit of 

 egg laying met with in this last tribe shows that it has been on this 

 course of development longer than has the Phyllaphidina. The 

 group is therefore considered as a tribe which has separated some- 

 what earlier and yet has paralleled in some ways certain characters 

 of the Phyllaphidina. 



Continuing with the Callipterus branch we find two somewhat 

 similar lines of development, the one represented by the Callipterina 

 and the other represented by the Chaitophorina. Both are similar 

 in many regards, but are quite different in the armature, particularly 

 of the antennse. 



The first sub tribe separating from that offshoot represented by 

 the Callipterina is the Phyllaphidina. This seems evident from the 

 fact that the oviparous forms of some species are yet alate, a primi- 

 tive condition found very seldom in the Aphididae. The next off- 

 shoot resulted in the Callipterina where the oviparous forms are apter- 

 ous, the cornicles of moderate development, and the wing veins 

 usually not reduced. From this offshoot the Saltusaphidina evi- 

 dently arose. This little subtribe is closely related to the Callip- 

 terina in many ways, but there are some new developments. In 

 the first place the power of leaping has become developed by the 

 enlarging of the femora. Secondly, both the sexual forms have lost 

 their wings, which the male usually retains in the Callipterina. One 

 of the most important points, however, is the fact that in the Sal- 

 tusaphidina the ocular tubercles which represent the retained larval 

 eyes are absent, whereas they are quite conspicuous in the Callip- 

 terina. 



On this same Callipterus branch, but somewhat more specialized 

 than the Callipterina, are two subtribes. These have specialized 

 in opposite directions, the one toward the elimination of the cornicles 



