658 M. W. R. de V. GRAHAM 



reaching the median ocellus ; pedicellus in dorsal view about twice as long as broad, therefore 

 slightly longer than in nobilis ; flagellum strongly clavate and relatively short, combined length 

 of pedicellus and flagellum 0-75 to 0-85 breadth of head ; first funicular segment very slightly 

 longer than the second segment, varying from quadrate to slightly transverse ; second segment 

 slightly transverse, the following segments progressively more so, the fifth varying from 1-6 to 

 1 -9 times as broad as long, the latter segment also is slightly longer than any of the preceding 

 ones ; clava short and broad, on the average about 1 -6 times as long as broad, its second suture 

 oblique. 



Pronotal collar very short medially, only one fifteenth to one twelfth the length of the meso- 

 scutum, not or only indistinctly margined. Propodeum medially one third or slightly more 

 than one third as long as the scutellum ; median area 1-9 to 2-1 times as broad as long, its 

 panels shiny and nearly smooth or with traces of weak reticulation. Fore wing with row of 

 hairs on lower surface of costal cell complete, or else broken in the middle, sometimes widely 

 so ; basal vein with three to six hairs ; marginal vein 1-85 to 2-15 times as long as the stigmal 

 vein ; postmarginal vein from two thirds to nearly three quarters as long as the marginal vein ; 

 stigma tending to be a little larger and more subcircular than in nobilis. Legs rather short ; 

 femora stout. 



Gaster ovate, 1-75 to 2-1 times as long as broad, from slightly shorter than, to 1-15 times 

 as long as, head plus thorax ; last tergite somewhat shorter than its basal breadth, usually 

 about 1-5 times as broad as long ; hind margin of basal tergite sometimes rather distinctly 

 emarginate medially ; gaster ventrally only moderately convex, the hypopygium extending 

 nearly or quite to half its length. Hypopygium (Text-fig. 550) with anterolateral angles rather 

 less prominent than in nobilis ; median sclerotized area rather shorter and broader, reaching 

 only a little farther back than the level of the hind edges of the sublateral sclerotized areas. 



The most reliable distinctions from the female of nobilis seem to be the relatively- 

 longer malar space of prasinus, and the shorter and more strongly clavate 

 flagellum with relatively shorter funicular segments of which the distal ones are 

 more strongly transverse. The gaster of prasinus is on the average shorter than 

 that of nobilis. Small females of nobilis may approach those of prasinus in the 

 shape of the antennal flagellum, but they have the distal segments of the funicle 

 less transverse, whilst their malar space is relatively shorter. 



o*. Similar to the female, but femora pale or brown at the base only ; scape stouter ; flagel- 

 lum with rather more conspicuous hairs ; clava beneath with a large collapsed area which 

 extends nearly to the base, this area and the last funicular segment thickly clothed with rather 

 short, outstanding hairs. 



Britain, Sweden, Austria. 



Biology. Von Rosen (1966 : 83) recorded having reared 4 $ from a laboratory 

 culture of Agropyron repens (L.) Beauv. infested with frit-fly, and according to 

 him imagines appear in Sweden in the spring. In England prasinus has so far 

 been captured in the field only in September : Isle of Wight (Walker, 1834) > 

 Dorsetshire, Lodmoor, near Weymouth, 13. ix. 1962, several <$$ and $$ swept from 

 a stand of Agropyron {Graham). Possibly the species has two generations per 

 annum. 



Mesopolobus laticornis (Walker), agg. 



This aggregate includes several puzzling forms which might prove to be " sibling 

 species " ; von Rosen (1966) in fact recognized 4 of the latter, all of which had been 



