1910] Key to the Genera of Aphidinae 323' 



Gen. Mastopoda Oestlund 



type pteridis Oestlund. 



Antennae about as long as the body, third segment shorter 

 than the spur of the sixth; first segment gibbous on the inner 

 side. Forehead nearly flat, body elongate, abdomen robust. 

 Wings long and slender, nectaries about one fourth the length 

 of the body and cylindrical. Cauda very short and conical, 

 anal plate broadly rounded. The atrophied tarsi and claws of 

 this genus are the most distinguishing characters. 



Gen. Coloradoa new genus 



type A. rufomaculata Wilson. 



Antennae about two thirds the length of the body, third 

 segment longer than the spur of the sixth which is only about 

 twice as long as the sixth. Wings moderately long, nectaries 

 one sixth as long as the body, cylindrical at the base and slightly 

 clavate at the end as in Rhopalosiphum. Cauda two thirds as 

 long as the nectaries and tapering; tip blunt. Caudal plate 

 broadly rounded. 



Gen. Cerosipha Del Guercio 



type passerinina Del Guerc. 



Antennae shorter than the body and with but five segments 

 and spur, third segment longer than the spur of the fifth. 

 Forehead nearly flat but slightly raised in the center. Body 

 elongate, abdomen the widest part of body. Wings long, 

 medium wide, wing venation regular with twice forked cubitus. 

 Nectaries about one tenth the length of the body and cylindrical, 

 with a very slight taper. Cauda slightly shorter than the 

 nectaries and tapering to a round point. 



Gen. Pergandeida Schouteden 

 type ononidis Schout. 

 Antennae about as long as the body, spur of sixth segment 

 as long as the third segment. Forehead with a prominent 

 tubercle supporting the frontal ocelli, and slightly raised at the 

 base of the antennae. Body elongated, stout; wings low and 

 broad with twice forked cubitus. Nectaries short stout and 

 tapering. Cauda as long as nectaries and broadly rounded at 

 the tip. Anal plate broadly rounded. 



