No. 22.] HYMENOPTERA OF CONNECTICUT. 367 



Cothonaspis Ashmead. 

 Probably occurs in the state. 



Xystus Hartig. 

 Allotria. 



X. brassicse Ashmead. Cabbage Aphis Xystus, or Cabbage 

 Aphis Allotria. 



This is a parasite of the cosmopolitan Aphis brassicce. Length 

 1.2 mm. Female: mostly black; face and vertex stramineous; 

 antennae pale yellowish brown, or yellowish toward base, becom- 

 ing brownish or inf uscated at the tip ; thorax smooth ; wings clear, 

 their veins yellowish ; second abdominal segment but slightly 

 longer than the third ; abdomen more or less stramineous at base 

 and beneath ; legs stramineous or tawny yellow. Male : with the 

 third, fourth and fifth joints of the antennas almost equal in 

 length, and each of these joints arched ; pleurae more or less 

 stramineous. 



X. avenae Fitch. Oat Xystus, or Oat Allotria. 



Length 1.5 mm.; mostly black; legs brownish; basal joint 

 of the antennae no thicker than the others, long, egg-shaped with 

 its smaller end downward, and tapering into a short pedicel which 

 is one-third the thickness of the joints and not as long as thick, 

 the joints near the apex scarcely diminished in thickness and not 

 at all in length, the apical joint egg-shaped ; wings hyaline with 

 a smoky tinge, their veins brown. 



X. tritici Fitch. 



Length 1.2 mm.; mostly black; head and legs pale yellowish; 

 basal joints of the antennae pale yellowish and more slender than 

 the others, about three times as long as thick, obovate, trans- 

 versely cut off at tip; second joint oval, twice as long as thick; 

 third and fourth joints each as long as both the preceding and 

 but half their thickness, slender ; fifth joint thicker, and the fol- 

 lowing ones gradually increasing in thickness until they become 

 equal in thickness to the basal joint ; the joints near the apex three 

 times as long as thick, and cylindrical, the terminal joint oval; 

 head about twice as broad as long, face and mouth pale yellowish, 

 vertex yellowish, with a blackish tinge; wings hyaline, slightly 

 smoky, veins brown ; end of abdomen blunt, with a thick papilla- 

 like projection from its middle. 



