468 



Wirth and Stone: Diptera 



4. Mesonotum opaque; 2nd costal section much longer than 

 3rd; Mono, Placer, Plumas, and San Bernardino counties 



occidentalis Cresson 1942 



— Mesonotum shining 5 



5. Face cinereous, broad and convex; 2nd costal section 

 about twice as long as 3rd; Los Angeles and Santa 

 Cruz counties valens Cresson 1942 



— Face black or sparingly dark pollinose, prominent at 

 upper facial; 2nd costal section not much longer than 

 3rd; California atrata Cresson 1940 



Key to Adults of the California Species of 



Hydrochasma 



1. Mouth opening very large; head subglobose, very broad; 

 fore femoral comb of numerous, minute spinules on 

 anterior margin; Los Angeles, Riverside, and San Diego 



counties capax Cresson 1938 



— Mouth opening not unusually large; head more flattened 

 in profile; fore femoral comb of several spinules on 

 posterior margin; Imperial, Los Angeles, and Sonoma 

 counties leucoprocta (Loew) 1861 



Genus Discocerina Macquart 



(Fig. 14:55*) 



According to Griinberg (1910), the European Disco- 

 cerina plumosa (Fallen) breeds in algae and moss 

 in the forest. 



Key to Adults of the California Species of Discocerina 



1. Parafacies with series of down-curved setulae 2 



— Parafacies bare 3 



2. Parafacies contrastingly paler in ground color, the 

 sparser vestiture augmenting this contrast; hind tro- 

 chanters of male without long caudal seta; California 

 obscurella (Fallen) 1813 



— Parafacies not noticeably differing from medifacies 

 either in ground color or vestiture; hind trochanters of 

 male with a long caudal seta; California 



trochanterata Cresson 1939 



3. Facial series of only 2 equally long bristles; southern 

 and central California nadineae (Cresson) 1925 



— Facial series of 3 or more equally long bristles; Kern, 

 Riverside and San Diego counties 



turgidula Cresson 1940 



Tribe DISCOMYZINI 

 Genus Clanoneurum Becker 



and carrion. The puparium of the latter has been 

 described and figured by Bohart and Gressitt (1951). 



Tribe PSILOPINI 



Key to Adults of the California Species of 



Ceropsilopa 



1. Femora mostly black; San Diego County 



dispar Cresson 1922 



— Femora and tibiae yellow 2 



2. Face shining, narrow and wrinkled; southern and cen- 

 tral California coquilletti Cresson 1922 



— Face entirely opaque, cinereous; Orange County .. 



staff ordi Cresson 1925 



Genus Trimerinoides Cresson 

 adfinis (Cresson) 1922. Kern County 



Genus Trimerina Macquart 



The larvae of the European Trimerina madizans (Fal- 

 len) are parasitic in eggs of spicers (Hennig, 1943). 



Genus Psilopa Fallen 



(Fig. 14:55/) 



The larvae of Psilopa leucostoma (Meigen) have been 

 reported as mining in species of Chenopodium in 

 Europe (Hennig, 1943). 



Key to Adults of the California Species of Psilopa 



1. Legs except mid- and hind-coxae yellow; face of male 

 silvery white; Riverside and San Mateo counties .... 

 leucostoma (Meigen) 1830 



— Coxae and femora black 2 



2. Antennae and fore tibia more or less yellow; face 

 flattened, the single pair of strong facials very low; 

 wing hyaline; California compta (Meigen) 1830 



— Antennae and fore tibia black; face more or less con- 

 vex, 2 pairs of facials usually present and compar- 

 atively high on face; wing usually with ends of 3rd and 

 4th veins infuscated; central and southern California 

 olga Cresson 1942 



Key to Adults of the California Species of 

 Leptopsilopa 



The larvae of Clanoneurum menozzii Se'guy mine in 1. Mid- and hind-legs entirely yellow; Douglas, Arizona 



leaves of beet in Europe (Hennig, 1943). • atrimana (Loew) 1878 



— All femora mostly black; mid- and hind-tibiae and their 



tarsi pale; California varipes (Coquillett) 1900 



americanum Cresson 1940. San Diego County 



Genus Discomyza Meigen 



Genus Helaeomyia Cresson 

 (Fig. 14:57<U<7) 



The larvae of Discomyza incurva (FalMn) and maculi- 



pennis (Wiedemann) have been bred from dead mollusks The larvae of Helaeomyia petrolei (Coquillett), the 



