442 



Wirth and Stone: Diptera 



margins which are only rarely extended; mesonotum 

 with thick gray pile; Sierra Nevada .nevadae Bigot 1887 



— Abdominal tergites with conspicuous markings on at 

 least the 2nd segment, if without, ventrites with con- 

 siderable yellow laterally 7 



7. Abdomen no broader than thorax, rather strongly convex 

 in transverse section; mesonotal pile cinereous; 3rd 

 tergite without transverse apical markings; California 

 griseata Curran 1923 



— Abdomen distinctly broader than thorax, only moderately 

 convex; mesonotal pile yellowish; 3rd tergite sometimes 

 with transverse apical or even broad lateral markings; 

 Sierra Nevada discaloides Curran 1923 



Genus Labostigmina Enderlein 

 similis (Johnson) 1895. Lake Tahoe 



Genus Hedriodiscus Enderlein 



The larva of the eastern H. vertebrata (Say) which 

 breeds in small streams cannot be distinguished from 

 those of Eulalia. 



Key to Adults of the California Species of Hedriodiscus 



1. Face prominent below the base of the antennae and 

 marked with a black spot on each side in ?; branches 

 of the media weak; length 10 mm. or less; Imperial 

 County trivittatus (Say) 1829 



— Face receding to the oral margin and in the ? wholly 

 pale; branches of media strong; length 12 mm. or more 

 2 



2. Mesonotum broadly margined with yellow, the disc with 

 2 yellow spots; scutellum entirely yellow; widespread 

 in California truquii truquii (Bellardi) 1861 



— Yellow markings of mesonotum greatly reduced 3 



3. Base of scutellum rarely and but narrowly black; pile 

 of scutellum pale; southern California 



truquii innotata (Curran) 1927 



— Base of scutellum black; pile of scutellum black; 

 Imperial County currani James 1932 



Genus Eulalia Meigen (=Odontomyia Meigen) 



The larvae resemble those of Stratiomys, but the 

 antennae are longer, the last segment of the body is 

 shorter, and there are one or two pairs of stout hooks 

 on the ventroposterior margin of the next to the last 

 segment and in some species also on the preceding 

 one (fig. 14:45rf). The larvae breed in small sluggish 

 streams or ponds, especially those with muddy bot- 

 toms, and feed on algae, small microorganisms, and 

 decaying vegetable matter. Brues (1928) records five 

 unnamed species from western hot springs. The fol- 

 lowing key to adults is adapted from James (1936c) 

 and the one on larvae from Johannsen (1922). 



Keys to the Adults of the California Species of Eulalia 

 Males (eyes contiguous) 



1. Eyes clothed with conspicuous pile; southern and 

 central California hirtocculata (James) 1936 



— Eyes bare 2 



2. Femora black, the apices often pale 3 



9, 



10 



Femora wholly yellow, at most reddish or brownish . 5 

 The pale markings on the 2nd abdominal segment reach- 

 ing toward and attaining, or nearly attaining, the base 

 of the segment; San Joaquin Valley . colei (James) 1936 

 The pale markings on the 2nd abdominal segment not 

 encroaching upon the basal half of the segment, usually 



narrower and linear 4 



Face unusually broad, the oral margin pale; vein R 4 

 distinctly present; southern and central California 



pilosa (Day) 1882 



Face of moderate breadth; the oral margin black; vein 

 R 4 usually absent; widespread in California 



hoodiana (Bigot) 1887 



Face above the depression wholly yellow, the frontal 



triangle sometimes black 6 



Face above the depression and the frontal triangle 



wholly black 9 



Lateral margins of mesonotum wholly green or yellow; 



Sonoma County cincta (Olivier) 1811 



Lateral margins of mesonotum black, the posterior calli 



sometimes pale 7 



Inner ocular orbits strongly bowed; the width of the 

 face across the oral margin greater than the distance 

 from the upper angle of the oral margin to the base of 

 the antennae; Riverside County. . . .tumida (Banks) 1926 

 Inner ocular orbits almost straight; the width of the 

 face across the oral margin about equal to the distance 

 from the upper angle of the oral margin to the base of 



the antennae 8 



Abdominal band as wide on the 2nd and 3rd segments 

 as on the 4th; in some cases the pattern on the 2nd 

 and 3rd segments is broken, so that the width must 

 include the separated marginal spots; southern and 



central California arcuata (Loew) 1872 



Abdominal bands definitely narrower on the 2nd and 

 3rd segments than on the 4th, and without separated 

 marginal spots; southern California 



alticola (James) 1932 



Oral margin yellow 10 



Oral margin black; Kern County. . .pubescens (Day) 1882 

 Face retreating below the antennae; California 



americana (Day) 1882 



Face with a keeled prominence below the base of the 

 antennae; Santa Clara County . .inaequalis (Loew) 1865 



Females (eyes widely separated) 





1. Eyes clothed with conspicuous pile 



hirtocculata (James) 



- Eyes bare 2 



2. Mesonotum with lateral yellow markings extending at 



least for a short distance in front of the suture 



cincta (Olivier) 



- Mesonotum wholly black in front of the suture, the 

 humeri sometimes yellow 3 



3. Posterior femora wholly, or at least half, black 4 



- Posterior femora yellow or at most reddish 5 



4. Vein R 4 present 6 



- Vein R 4 absent hoodiana (Bigot) 



5. Front wholly black; head unusually wide. . .pilosa (Day) 



- Front with yellow markings along the midfrontal suture 

 and to each side of the ocellar triangle; head of normal 

 width colei (James) 



6. Head chiefly black, more or less marked with yellow; 

 dorsum of thorax wholly black, at most the posterior 

 calli yellow 7 



- Head yellow, marked with black; sides of mesonotum 

 yellow at least along the wing bases; humeri yellow 

 8 



7. Abdomen black in ground color, with pale transverse 

 linear markings at the posterior margins of the segments 

 pubescens (Day) 



- Abdomen pale in ground color, with a dorsal black 

 stripe which may, however, be almost the width of the 

 abdomen americana (Day) 



8. Face with median black or brown vitta which widens 



