\52 INSECUTOR INSCITI/E MENSTRUUS 



sooty dorsally, subpruinose. Thorax shining blue-black, with white pile 

 dorsally and on the pleurae. Scutellum large, dull yellow, broadly blue- 

 black on the sides, the hmrs long, whitish. Abdomen dorsally shining 

 violet-black, with black velvety fasciae on segments 2 to 5 and yellow 

 fasciae on segments 3 and 4 ; second segment with a broad, straight, 

 velvet-black fascia behind the basal third, extending to the lateral mar- 

 gins and leaving a narrow, shining posterior margin ; third segment with 

 a broad yellow fascia situated medianly, very slightly arcuate, of nearly 

 equal width throughout and extending close to the lateral margins, pre- 

 ceded and followed by narrower velvet-black fasciae, leaving the anterior 

 and posterior margins of the segment, and more narrowly the lateral mar- 

 gins, shining violaceous ; fourth segment with a broad yellow fascia sub- 

 medianly, straight on its anterior margin, shallowly emarginate on its pos- 

 terior margin and not atteuning the lateral margins of the segment, preceded 

 by a nzuTow and followed by broad fascia of velvet-black, the anterior, 

 posterior, and lateral margins of the segment shining violaceous ; fifth seg- 

 ment with a large median velvet-black fascia, leaving the margins shining 

 violaceous ; lateral hairs whitish, long on the first two segments. Legs 

 dull ferruginous, the femora dark at base, the tarsi infuscated distally ; 

 hind femora with a black ring close to apex, the hind tibiae with less dis- 

 tinct dark rings near base and close to apex. Wings hyaline, the sub- 

 costal cell yellowish brown ; third vein gently but distinctly arcuate above 

 the first posterior cell. Halteres with fenuginous brown knob. 



Length : Body, 8 mm. ; wing, 8 mm. 



Female : Frons broad, shining black, a broad arcuate fascia of whitish 

 pollen across the middle and extending forward at the sides, a yellow 

 lunate spot just before antennae ; median stripe of face blackish. Abdo- 

 men with the yellow fasciae of segments 3 and 4 before their middle, 

 straight on the anterior margins, gradually narrowed to the middle on 

 their posterior margins, the velvet-black fasciae preceding them very nar- 

 row, the ones behind them broad and following their contour ; back 

 fascia of fifth segment somewhat before middle ; segments 2 to 5 with 

 broad shining posterior margins ; sixth segment wholly shining black. 



Length : Body, 9 mm. ; wing, 8 mm. 



Localities: Walnut Creek, California, June, 1914, one male, one 

 female (W. M. Davidson) ; California, one male ; Williams, Arizona, 

 July 27, one female (Schwarz & Barber). 



Type, Cat. No. 19037, U. S. Nat. Mus. 



