429 

 Wirth and Stone: Diptera 



Fig. 14:41. Heleidae, immature stages. a,b, Atrichopogon peregrinus (Joh.): o, larva; b, pupa. 

 c, Bezzia glabra (Coq.), pupa, d, Stilobezzia bulla Thomsen, pupa (Thomsen, 1937). 



segments; eyespots present; dorsolateral rods of 



pharyngeal apparatus present kerteszi Kieffer 



— Mature larva whitish; body with apparently 21 segments; 

 eyespots absent; dorsolateral rods of pharyngeal 

 apparatus aDsent (fig. 14:40a) torrens (Townsend) 



Subfamily FORC IPOMYI INAE 



Genus Atrichopogon Kieffer 



The species of this genus are mostly aquatic, but 

 one very common North American species, levis 

 (Coquillett), breeds in soil at the roots of lawn grass. 

 The biology and immature stages of several aquatic 

 North American species were discussed by Thomsen 

 (1937), and one of the best biological papers on this 

 genus was recently published by Nielsen (1951). The 

 immature stages commonly occur on wet stones in or 

 beside small streams, on floating logs, in blanket 

 algae in ponds, or on the sides of tanks or concrete 

 pools. The larvae have flattened bodies with promi- 

 nent, segmental, dorsal, and lateral processes (fig. 

 14:41a). Larval and pupal characters (fig. 14:416) of 

 the few known species are good, but many groups of 

 adults can be separated only by quantitative char- 

 acters, and many of the species keyed out below are 

 probably complexes. Several s'pecies suck the blood 

 of blister beetles (Meloidae). 



species (length 2.0 mm.); widespread throughout Cali- 

 fornia fusculus (Coquillett,) 1901 



— Proboscis not longer than height of head; clypeus with 

 base truncate or not strongly produced between anten- 

 nae; size smaller (1-1.6 mm.) 2 



2. Scutellum yellow with 4 long, black, marginal bristles; 

 humeri usually extensively yellow; antennae long, 

 distal segments about 3 times as long as broad; wings 

 nearly bare; widespread levis (Coquillett) 1901 



— Scutellum dark brown; mesonotum brown or black. . . 3 



3. Scutellum with 2 bristles; wing nearly bare; small, 

 polished black species ; Humboldt and Siskiyou counties 



mintitus (Meigen) 1830 



— Scutellum with 4 bristles 4 



4. Mesonotum usually with a sublateral pair of translucent 

 brown lines from ends of scutellum to humeral depres- 

 sions; mesonotal setulae in rows; widespread 



websteri (Coquillett) 1901 



— Mesonotum without translucent lines, with dense 

 scattered setae 5 



5. Wing nearly bare, macrotrichia confined to tips of 

 cells R s and M,; 7th abdominal sternite with median, 

 forked, spinous appendage; Humboldt, Siskiyou, Modoc, 

 Tulare, and Monterey counties; Transition Zone 



arcticus (Coquillett,) 1900 



— Wing with extensive macrotrichia at least to cell M 2 ; 

 7th sternite unmodified 6 



6. Macrotrichia only to cell M 2 ; mesonotum shining; distal 

 antennal segments each twice as long as broad; eyes 

 pubescent; Transition Zone of northern Coast Ranges 

 and Sierra Nevada transversus Wirth 1952 



— Macrotrichia to middle of anal cell (fig. 14:38*); distal 

 antennal segments 3 times as long as broad; eyes 

 bare; northern and central California 



occidentalis Wirth 1952 



Keys to Adults of the California Species of Atrichopogon 



Females 



1. Proboscis about 1.4 times as long as height of head; 

 clypeus triangularly produced between antennae; large 



Male Genitalia 



1. Ninth sternite deeply excavated in middle 3rd of poste- 

 rior margin, with marginal hairs not extending entirely 



across sternite (fig. 14:38,/') 2 



— Ninth sternite transverse or shallowly and broadly 



