8 



approximated ; scutellum velvety black, the sides iridescent ; pleurae 

 blaek; sternum yellow; bases of legs yellow but the outer half of all 

 the femora and remaining portions of the legs a little darkcned; hind 

 tarsi but little dilated and thickly with nnmeroiis üior*^ daik bristles. 



Abdomen : — Velvety black, with an iridescent spot on the side of 

 each of the first six segments. 



Wings : — Clear with f aint iridescent reflections ; f ourth vein 

 rnidway between the anterior crossvein and its apex. Haltere black. 



Female : — Very similar to the male. The front broad, widen- 

 ing upwards and wath an iridescent spot completely covering it below 

 the ocelli. Sixth sternite with a row of five bristles. 



Two males, four females, taken while on the surface of big leaves 

 of low growing plants in shady woods. 



Type locality. — Quebrada de Lules, Tucumán, (2 Febrnary, 1927, 

 R. C. Shannon). Also from Raeo, Tucumán, (13 February, 1927, R. C. 

 Shannon). 



Family Pipunculidae. 



Thinly pilóse or nearly bare flies, practieally without bristles. 

 Head very large subhemispherical, formed almost entirely of the eyes. 

 Antenna with a dorsal arista; wings much longer than abdomen; last 

 section of fourth vein curved forwards but does not joint the third. 

 Tibiae without spurs. Ovipositor heavily chitinized, exserted. 



A very distinct family composed of usually small and dark flies. 

 They possess remarkable powers of hovering and poising in the air. 

 The larvae are endoparasites of other insects, mainly Homoptera. 



Four species of the genus Pipuncnlus are at hand but probably 

 tvventy or more will eventually be found in Argentina. They may be 

 separated as foUows: 



Key to species of Pipunculus. 



1. Subcostal cell without stigma; tip of second vein much nearer 

 the auxiliary vein than to the third vein Pipunculus lynchi. 

 Subcostal cell with well defined stigma; tip of second vein 

 nearer to the third vein 2. 



2. Third antennal joint without a long tapering process directed 

 downwards ; tergites dark with light gray posterior bands . . 

 Pipunculus doell'oi. 



Third joint with a long tapering process directed downwards; 

 abdomen without distinct crossbands 3. 



3. Legs yellow with indefinite darkened áreas on the exterior 



sides of the femora ; third antennal joint palé yellow 



Pipunculus schreiteri. 



Legs yellow with broad black irregular bands surrounding 

 the greater portion of the femora; third antennal joint 



blackish, the lower apex faintly yellow 



Pipunculus tucumanus. 



