AMERICAN DIPTERA. 221 



I have seen material from Florida, Louisiana and Mexico, 

 showing almost every gradation from the black form of tristis 

 up to phcenicums, and believe that the latter is only an ex- 

 treme variation of the former. I am, however, in some doubt 

 as Dr. Williston has seen and described in Biologia, female 

 specimens of lucas, phcenicurus, and possibly tristis. Larger 

 collections will bring out interesting facts. 



Dizonias pilatei (PI. VII, fig 2.) 



Dizonias pilatei Johnson, Psyche, X, 112, fig. 5, 1903. 



9- — Length 16 mm. — Yellowish-red, head, pleurae, lateral margins 

 of thoracic dorsum, scutellum and a broad band on the basal portion 

 of abdominal segments 1-5, golden pruinose; legs wholly reddish- 

 yellow with pale fine hair and short black bristles; all the rest of the 

 clothing of the body yellowish. Wings brownish, the discal portion 

 and the veins bordered with yellow. 



Head, except ocellar tubercle, thickly golden pruinose; antennae, 

 palpi and the lower half of the proboscis reddish; the mystax, hair 

 of proboscis, palpi, beard, frontal orbits and ocellar tubercle and the 

 bristles of the occiput whitish. Thorax rather narrow, dorsum de- 

 cidedly reddish, with a broad median and two lateral black stripes, 

 the latter greatly abbreviated anteriorly and distinctly bisected by 

 the transverse suture; the whole dorsum faintly obscured by a bloom, 

 the lateral margins, especially when viewed from the side, rather densely 

 golden pruinose. Pleurae reddish, with suggestions of black in places; 

 golden pruinose in varying degrees of intensity, being most prominently 

 so on the mesopleurae, a spot above each coxae, and before and above 

 the halteres; scutellum likewise golden pruinose. Halteres pale yel- 

 low. Abdomen yellowish-red; the extreme base of the first segment 

 and the posterior margin of segments 1-4 almost velvety black, the 

 larger part of the tergum on segments 2-3 blackish; segments 1-5 

 with a broad basal yellowish pruinose band, that on the second and 

 third segments occupying the entire lateral margin and gradually 

 narrowing above; segments 5-8 polished, reddish-yellow. Venter 

 black or blackish, toward the tip of the abdomen reddish. Legs, in- 

 cluding the coxae, wholly reddish-yellow, the coxae golden pruinose; 

 hair of legs short, pale yellow, all the bristles short, black; pul villi 

 pale; claws black, reddish on basal half. Wings brownish, almost 

 blackish on the costa; the center of the cells, the borders of the veins 

 more yellowish. 



Type. — Collection of Prof. W. C. Johnson, Curator of the 

 Boston Society of Natural History. A single female in ex- 

 cellent condition. 



TR.\NS. AM. ENT. SOC, XXXV. JUNE, 1909. 



