474 



Wirth and Stone: Diptera 



— Acrostichals usually irregular in size and position, 

 rarely forming 2 regular rows to scutellum; reclinate 

 orbital not so far forward; mesonotal pattern usually 

 evident 9 



9. With a stout pair of presutural acrostichal bristles, 

 as long as the ocellart, or nearly so; small dark species 

 with gray mesonotal pattern, highly spotted wings, 

 black legs, strong head bristles; faces of the 2 sexes 

 similar; Los Angeles and Santa Barbara counties 

 . . .• exilis Cresson 1935 



— Without presutural acrostichal bristles though 1-2 

 pairs of hairs in this region are often enlarged; faces 

 of the sexes unlike, that of the male concave, flattened, 

 protuberant, incised, tuberculate, or otherwise modified 

 from the female type 10 



10. Abdomen black, noticeably shining, especially on 

 apical tergites, the basal tergites with at most thin 

 pollen 11 



— Abdomen brown to black, rather heavily pollinose, 

 rarely a bit glossy but never appearing truly shining 



12 



11. Cheek about as wide as width of 3rd antennal segment; 

 frontal triangle scarcely differentiated in color from 

 the anterior nonorbital areas; mesonotum usually with 

 an olive tint; palpi pale, tarsi usually partly pale; 

 Los Angeles and San Francisco counties 



viridella Sturtevant and Wheeler 1954 



— Cheeks narrower than width of 3rd antennal segment; 

 frontal triangle and orbits dull brown, leaving 2 black 

 triangular areas anteriorly on front; palpi and tarsi 

 mostly dark; male face sunken in middle, usually 

 membranous to a noticeable degree, the oral margin 



protuberant; southern California 



rubribrunne a Sturtevant and Wheeler 1954 



12. Wing base yellow, the blade with conspicuous pattern; 

 scutellum with distinct basal gray triangle; male face 

 flat to concave, the margin protruding, golden yellow; 



Los Angeles County 



hesperia Sturtevant and Wheeler 1954 



— Wing base not strongly yellowed; scutellum with indis- 

 tinct basal gray area or none; face more brown than 

 yellow, that of male protruding at margin, with an 

 elongate median depression bordered (especially 

 anteriorly) by dense curly hairs; female face with some 

 glossiness; Alameda County 



variofacialis Sturtevant and Wheeler 1954 



Key to Adults of the California Species of 

 L imnel lia 



First posterior cell with 3, small, round, isolated, 

 dark spots not contiguous with 3rd vein and similar to 

 the 2 spots in submarginal cell; central California 



sejuncta (Loew) 1863 



First posterior cell with 3, prominent, quadrate, dark 

 spots contiguous on anterior side with 3rd vein; sub- 

 marginal cell usually without small, round, isolated, 

 dark spots; central California . . .quadrata (Fallen) 1813 



Genus Scatella Robineau-Desvoidy 



The biology and immature stages of S. thermarum 

 Collin, a species very closely related to our stagnalis 

 (Fallen) (fig. 14:54a-c), have been well described by 

 Tuxen (1944), who found it breeding in large numbers 

 in the hot springs of Iceland. Brauns (1939) and Hen- 

 nig (1943) have given notes on the European species 

 subguttata (Meigen). The adults feed on algae at the 



water surface, rasping off particles with their probos- 

 ces. The larvae are strictly aquatic, crawling through 

 and feeding on the growths of algae and diatoms of 

 their preferred habitats near the surface. The boat- 

 shaped puparia (fig. 14:546) are found in the same 

 places as the larvae. 



Key to Adults of the California Species of Scatella 



1. Face silvery white; legs, pleura and sides of meso- 

 notum and abdomen silvery gray; wings hyaline, mark- 

 ings very faint; California paludum (Meigen) 1830 



— Face gray or brown; legs, pleura, sides of mesonotum 

 and abdomen dark brown to blackish 2 



2. Face gray 3 



— Face brown 4 



3. Scutellum with strong basal bristle in addition to the 

 usual weak downcurved seta near apex; California 

 troi Cresson 1933 



— Scutellum without strong basal bristle; California 

 laxa Cresson 1933 



4. Body entirely dull brownish pollinose; wing spots 

 indistinct; male with basal section of costa swollen 

 about 4 times normal thickness; Los Angeles County 

 obsoleta Loew 1861 



— Mesofrons and mesonotum usually subshining; wing 

 spots distinct; male costa normal 5 



5. Face tending vertical, the hump very prominent; light 

 spot in submarginal cell very prominent, quadrate, 

 entirely filling cell; size larger; California 



stagnalis var. pentastigma (Thomson) 1868 



— Face more sloping toward epistoma; the hump smaller; 

 light spot in submarginal cell rounded and not filling 

 cell; smaller species; California 



stagnalis (Fallen) 1813 



Genus Neoscatella Malloch 



(Figs. 14:54?; U:5Gg,k,l) 



The biology and immature stages of several Hawaiian 

 species of Neoscatella, which have been admirably 

 described and figured by Williams (1938), are essen- 

 tially the same as those of Scatella. 



setosa (Coquillett) 1900. California 



Key to Adults of the California Species of 

 Parascatella 



1. Mesonotum and scutellum dull; southern California 



triseta (Coquillett) 1902 



— Mesonotum and scutellum shining 2 



2. Face white, with dark spot on the median hump; wing 

 spots indistinct; intermediate frontobrbital seta at 

 least 1/2 as long as the 2 frontobrbital bristles; central 

 California marinensis Cresson 1935 



— Face entirely cinereous to brown; wing spots rather 

 distinct; intermediate frontobrbital seta minute; coastal 

 transition of California melanderi Cresson 1935 



Key to Adults of the California Species of 



Lamproscatella 



1. Face and pleura white 2 



— Face and pleura brownish 4 



