396 



Wirth and Stone: Diptera 



— Tarsi all dark or at least without definite basal seg- 

 mental bands 10 



2. Tarsal pale bands overlapping the joints 3 



— Tarsal pale bands basal only 4 



3. Wing with a few to many scattered pale scales: ab- 

 domen with median dorsal pale stripes or mostly pale; 

 band covering joint of hind tarsal segments 1 and 2 

 about equal on both segments; mesonotum with a median 

 darkened stripe of scales on anterior half at least; 

 Siskiyou County to Imperial County 



dorsalis (Meigen 1830) 



— Wing, except at extreme base, with all dark scales; 

 abdomen without a median dorsal pale stripe; band 

 covering joint of hind tarsal segments 1 and 2 much 

 larger on 1; mesonotum with a median stripe of golden 

 scales on anterior 1/2; Del Norte County to Riverside 

 County varipalpus (Coquillett 1902) 



4. Basal pale bands of 3rd hind tarsal seginent covering 

 less than 1/5 of segment as seen from front; basal pale 

 bands of 4th and 5th abdominal tergites indented 

 medially or divided into 2 spots; Modoc County to 

 Imperial County vexans (Meigen 1820) 



— Basal pale band of 3rd hind tarsal segment covering 

 1/3 or more of segment as seen from front; basal pale 

 bands of tergites not conspicuously indented medially 



5 



5. Wing scales mostly pale; abdomen largely yellow; a 

 large mosquito; Shasta County 



flavescens (Mueller 1764) 



— Wing scales not mostly pale; abdomen with numerous 

 dark scales, often with a tendency toward a median 

 stripe 6 



6. Wing, except at extreme base, with all dark scales; 

 proboscis with a median band of pale scales; palpus 

 tipped with pale scales; Orange County and Ventura 

 County taeniorhynchus (Wiedemann 1821) 



— Wing with a mixture of pale and dark scales 7 



7. Palpus all dark; proboscis sometimes with a median 

 patch or band of pale scales; Siskiyou to Kern counties 



nigromaculis (Ludlow' 1907) 



— Palpus with some pale scales; proboscis dark or with 

 mixed pale and dark scales 8 



8. Pale wing scales confined almost entirely to front 

 part of wing; torus with a few inconspicuous pale 

 scales on inner surface; Modoc County to Los Angeles 

 County , . . . . increpitus Dyar 1916 



— Pale wing scales scattered generally over wing; torus 

 with a conspicuous inner patch of pale scales 9 



9. Hind wing margin at base of fringe bordered with mixed 

 black and white scales; wing scales mostly very broad; 

 Sonoma to Riverside counties 



squamiger (Coquillett 1902) 



— Hind wing margin at base of fringe bordered with 

 minute unicolorous scales; wing scales narrow to 

 moderately broad; Shasta County to El Dorado County 



fitchii (Felt and Young 1904) 



10. Wing with scattered to numerous whitish scales along 

 costa, subcosta, and radius 11 



— Scales of costa, subcosta, and radius dark except for 

 basal spots which are about as long or shorter than 

 halter 13 



11. Palpus with all dark scales; subspiracular area of 

 pleuron with a lower scale patch only; abdominal 

 tergite 2 with pale band usually narrowed at middle 

 or divided; Shasta County to Mariposa County; high 

 Sierra ventrovittis Dyar 1916 



— Palpus with numerous pale scales, especially toward 

 base; subspiracular area with 2 scale spots, 1 directly 

 below spiracle; abdominal tergite 2 with pale band 

 broadened at middle 12 



12. Palpus not much longer than twice greatest diameter of 

 torus; mesonotum with slender or only slightly broad- 

 ened scales between spiracle and mid-line of meso- 

 notum; Shasta County to Mariposa County 



cataphylla Dyar 1916 



— Palpus much longer than twice greatest diameter of 

 torus; mesonotum with a large patch of pale broadened 



curved scales centered midway between spiracle and 



mid-line of mesonotum; Lake County 



bicristatus Thurman and Winkler 1950 



13. Vertex with a submedian black scale spot; basal pale 

 bands of abdominal tergites forming lateral spots which 

 join into a continuous lateral line; Modoc County to 

 Mariposa County cinereus Meigen 1818 



— Vertex without a definite submedian black scale spot; 

 abdomen usually without a continuous lateral line 



14 



14. Base of costa with a long pale spot; subspiracular 

 area with 5 scale spots, 1 directly below spiracle; 

 upright scales of vertex golden; Mono County and 

 Tuolumne County pullatus (Coquillett 1904) 



— Base of costa without a long pale spot; subspiracular 

 spot of scales absent 15 



15. Supra-alar bristles black; upright forked scales of 

 vertex mixed pale and dark; mesonotum with scaling 

 diffuse or forming a median line and submedian lines 

 which are largely fused with lateral areas; mesonotal 

 scaling golden to creamy; Shasta County to Mariposa 

 County ' communis (Degeer. 1776) 



— Supra-alar bristles not black; upright forked scales of 

 vertex pale, straw-colored 16 



16. Supra-alar bristles straw-colored; abdominal tergal 

 bands not markedly incised to form an inverted V on 

 tergites 5 and 6; mesonotum usually with middle 1/3 

 brownish yellow and side more golden; Shasta County 

 to Mariposa County hexodontus Dyar 1916 



— Supra-alar bristles amber to brown; abdominal tergal 

 bands markedly widened laterally and forming an 

 inverted V on tergites 5 and 6; mesonotum with a 

 narrow median pale line (often indistinct) flanked by 

 wider coppery lines, sides light straw-colored; San 

 Joaquin and Yolo counties sticticus (Meigen 1838) 



Male Genitalia 



Claspette absent, or fused to basistyle and without 



a filament 2 



Claspette present, attached at base only (fig. 14:16rf) 



3 



Dististyle unequally bifurcate near base, longer branch 



equally bifurcate at apex cinereus Meigen 



Dististyle broad, flattened, not bifurcate; apex blunt 

 with tooth borne at inner apical four-fifths 



vexans (Meigen) 



Filament (distal part) of claspette short, not bladelike 



bicristatus Thurman and Winkler 



Filament of claspette bladelike 4 



Basal lobe of basistyle with bristles which are nearly 

 equal in size or grading from small to large, but without 

 a single bristle distinguished by its greater size .... 5 

 Basal lobe of basistyle with a single stout bristle or 

 spine distinguished by its greater size, sometimes with 

 smaller spines in addition to slender bristles (fig. 



14:16d) 8 



Apical lobe of basistyle present; claspette filament 



with a sharp angle on convex side increpitus Dyar 



Apical lobe of basistyle undeveloped 6 



Claspette filament with a retrorse projection 



taeniorhynchus (Wiedemann) 



Claspette filament without a retrorse projection .... 7 

 Basal lobe of basistyle a dense clump of long, stout, 

 apically curved bristles of which longer ones are about 

 4 times as long as tooth of dististyle 



varipalpus (Coquillett) 



Basal lobe of basistyle a small clump of slender nearly 

 straight bristles of which longer ones are about 2.5 to 

 3 times as long as tooth of dististyle 



nigromaculis (Ludlow) 



Basal lobe of basistyle with 1 or 2 unusually stout 

 bristles in addition to long stout one (fig. 14:16fif). . . 9 

 Basal lobe of basistyle without differentiated bristles 

 other than a long stout one 10 



