20 BULLETIN 826, U. S. DEPARTMENT OF AGRICULTURE. 



Genus NEOTRAMA, n. gen. 

 Plate III, M, O. 



Head somewhat flat. In the apterous form the eyes reduced ; antennse of six segments 

 and the cornicles on very small cones with a few scattered hairs. Cauda subcorneal, 

 rounded. Anal plate rounded. Entire body covered with fine hairs. Hind tarsi 

 greatly elongate. 



Type, Trama troglodytes Del Guercio (=Neotrama delguercioi Baker). 



Tribe THELAXINI. 



It has been the custom of most writers to place the Thelaxini 

 (Vacuini) in the Eriosomatinae, often possibly because of the fact that 

 only one egg is laid by the oviparous female. But the female is quite 

 different in structure from the beakless females of the Eriosomatinae 

 and the other forms are very different indeed. 



With the Hormaphidinae there are more resemblances, the most 

 striking of which is the structure of the thorax. The mesothorax 

 indicates very faintly the lobes so prominent in most forms. The 

 presence of distinct cornicles, however, is very different from the 

 forms in the Hormaphidinae lacking these although possessing a some- 

 what similar thorax. 



The sensory structures, too, are widely different, being similar to 

 those found in the Phyllaphidina. Indeed, the antennae are very like 

 those of that subtribe. The oviparous forms of the Phyllaphidina, 

 however, lay several eggs and may be either winged or apterous and 

 the males, though sometimes apterous, are usually winged. The 

 venation of the Thelaxini is more reduced than in the Phyllaphidina. 

 Taking all of these facts into consideration it seems evident that the 

 Thelaxini should be placed in the Aphidinae and somewhat related to 

 the Phyllaphidina, a subtribe which belongs in the Callipterini. It is 

 evident, however, that the Thelaxini must stand somewhat apart; 

 it is placed, therefore, as a tribe of the subfamily Aphidinae next to 

 the Callipterini. In this tribe the specialization of the ovipara has 

 advanced beyond that of the Callipterini in that only one egg is laid, 

 but according to Buckton several eggs may be laid and the distinct 

 beak is evidence of relationship. 



Characters. — Cornicles present as chitinized rings on shallow hairy cones. An- 

 tennae somewhat setose, with oval or subcircular sensoria. Cauda somewhat semi- 

 circular or distinctly knobbed. Body usually armed with hairs or stout spines. 



Sexual forms small and apterous, possessing beaks; oviparous female as a rule laying 

 only one egg. 



Forms living free upon the foliage. 



The genera may be separated by the following key: 



Key to the Genera of the Thelaxini. 



Cauda distinctly knobbed Thelaxes. 



Cauda not knobbed but somewhat semicircular Glyphina. 



