GENERIC CLASSIFICATION OF APHIDIDAE. 23 



cies described as Symydobius albasiphus by Davis and here placed as 

 Neosymydobius. 



The internal structure of insects of this tribe appears not to differ 

 markedly from the structure in other groups. Witlaczil, however, has 

 reported that in certain members of this tribe the intestine forms a 

 closed loop almost similar to that found in the Chermidae. 



As a rule, in this tribe, the various forms met with in the subfamily 

 occur. In the genus Monellia, however, in some species at least, ap- 

 terous viviparous forms seldom occur, nearly all the viviparous forms 

 being alate. 



The sub tribes may be separated by the following key: 



Key to the Subtribes op the Callipterini. 



1. Eyes with ocular tubercles present, head not elongate 2. 



Eyes without ocular tubercles present, head often elongate Saltusaphidina. 



2. Antennae armed with rather long, prominent hairs 3. 



Antennae usually only with minute, sometimes stout bristles 5. 



3. Cornicles absent Fullawayina. 



Cornicles present - 4. 



4. Cornicles cylindrical or vasiform Pterocommina. 



Cornicles truncate, enlarged at base Chaitophorina. 



5. Cornicles absent above Monaphidina. 



Cornicles present, position as usual 6. 



6. Cornicles reduced to mere rings; large lateral abdominal wax plates 



present Phyllaphidina. 



Cornicles usually not reduced to mere rings ; no large abdominal wax plates 

 present 7. 



7. Cornicles variable, often long and somewhat swollen; oviparous female 



with an elongate ovipositor Drepanaphidina. 



Cornicles never long; always short and truncate; oviparous female not always 

 with an elongate ovipositor Callipterina. 



Sub tribe PHYLLAPHIDINA. 



The subtribe Phyllaphidina is erected for the species related to the 

 genus Phyllaphis. Many of the characters show these species as 

 quite closely related to the Callipterina, while in other ways they very 

 strongly suggest the Thelaxini, as indicated under the discussion of 

 the tribe. 



Characters. — Cornicles present; antennae of six segments, minutely setose, sensoria 

 elongate or subcircular; cauda knobbed or rounded, anal plate often bilobed, wax 

 glands present. Forms living free or in pseudogalls. Sexual forms often alate, some- 

 times, however, apterous or intermediate, showing that the apterous condition has 

 developed but recently; oviparous female producing several eggs. 



Key to the Genera op the Phyllaphidini. 



1. Anal plate deeply cleft and U-shaped Shivaphis. 



Anal plate entire or somewhat bilobed, not deeply cleft 2. 



2. Cauda rounded, anal plate entire 3 . 



Cauda knobbed, anal plate somewhat bilobed Phyllaphis. 



3. Oviparous females with annular sensoria Neophyllaphis. 



Oviparous females with small transverse sensoria Tamalia. 



