ART. 10 



NOETH AMERICAN TACHINID FLIES WEBBER 



23 



fourth its size. Frontal vitta variable in breadth and outline, 

 usually the sides nearly parallel from base of antennae to the lowest 

 ocellus, sometimes rapidly divergent. Front, outside of frontal 

 rows, in male sparsely bristly or sometimes with one to three bristles 

 the size of the weakest frontals, in female this region very weakly 

 hairy. Occiput slightly swollen below. 



Thorax black, gray pollinose, variable in density and usually with 

 a goldent cast. Thoracic chaetotaxy : Before the suture, acrostichal 

 3; dorsocentral 3; posthumeral 3; humeral 3; presutural 2; behind 

 the suture, acrostichal 3; dorsocentral 3; intraalar 3; postalar 1. 

 Scutellum black, gray pollinose, the tip often yellowish or red and 

 bearing three pairs of marginal bristles besides the usually cruciate 

 apical pair which are rarely parallel. Sternopleura usually with 

 four bristles. Ptero- 

 pleural bristle small, 

 about the size of the 

 weakest sternopleural 

 bristle. 



Abdomen black, gra}^ 

 pollinose, with or with- 

 out a yellowish tinge, 

 the pollen variable in 

 density although as a 

 rule much more thickly 

 pollinose than in 

 frenchii; sides of second 

 segment concolorous 

 with the rest of the abdomen or reddish. First segment usually 

 without median marginal bristles, although sometimes a weak pair 

 are present; second segment with one pair median marginal, or 

 rarely without anj': third with marginal row, fourth with a weak 

 marginal row and a much stronger submarginal one. Basal three- 

 fourths of this segment destitute of strong bristles. Abdominal hairs 

 depressed. 



Legs black, sometimes broAvnish, mid tibiae usually with one 

 strong and one weaker bristle above it or only one strong bristle on 

 outer front side. tAvo hind bristles, the uppermost a little above 

 the middle, and also a strong inner bristle just below middle. 

 Tibial spurs as usal. Hind tibiae evenly ciliated with one longer 

 bristle. Wings hyaline, third vein with two or three bristles at 

 base; costal spine short, scarcely discernible. 



Genitalia (figs. 10, 11) black in most part, outer forceps brown- 

 ish; forceps viewed from behind at widest part over one-half as 

 Avide as long; viewed in profile, the inner forceps slender, tapering 

 slightly to fine points, almost straight, and with a \^ery slight concav- 



FlGUEES 10 AND 11. ACHAETONEDRA AKCHIP- 



PIVOHA (WiLLISTON), MALE GENITALIA. 10, FEOM 

 BEHIND ; 11, SIDE VIEW 



