26. Furcation without a distinct dark spot, although entire 

 wing may be infuscated; mesonotum and fore tibia black 



27 



— Furcation usually with a distinct dark spot; mesonotum 

 covered with creamy hair over a dark reddish back- 

 ground; fore tibia bicolored; Del Norte County to 

 Imperial County punctifer Osten Sacken 1876 



27. At least tergite 1 with an inconspicuous tuft of white 

 hairs beneath the scutellum; frontal callosity subquad- 

 rate, the median callus narrow; El Dorado and Santa 

 Clara counties kesseli Philip 1950 



— None of tergites with median tufts of white hairs; 

 frontal callosity merging broadly with median callus 

 above; Humboldt, Sonoma, and Santa Cruz counties 

 aegrotus Osten Sacken 1877 



28. Base of vein R 4 with stump vein; Sierra, Inyo, and San 



Luis Obispo counties productus Hine 1904 



Base of vein R 4 without stump vein 29 



29. Eyes pilose; median spot a triangle on tergite 2; Mono 

 County stonei Philip 194 1 



— Eyes bare; median spot on tergite 2 rectangular .... 30 



30. Outer hind tibial fringe mostly black; body markings 

 contrasting; front usually evenly convergent; Trinity 

 County to Imperial County 



lineola scutellaris Walker 1850 



— Outer hind tibial fringe mostly white; body color faded 

 in appearance, the middorsal stripe not especially paler 

 than the sublateral ones; frontal margins rather bowed 



in the middle; Riverside and Imperial counties 



.vittiger nippontucki Philip 1942 



31. Eyes pilose 32 



— Eyes bare, or only sparsely pilose 33 



32. Abdomen with a median row of pale spots forming a 

 parallel-sided stripe; upper eye facets greatly enlarged 

 vittiger nippontucki Philip 



— Abdomen without a parallel-sided stripe; 4 black spots 

 on abdominal tergite 2; upper eye facets not greatly 

 enlarged laticeps Hine 



33. Abdomen unicolorous, black (rarely a median row of 

 small whitish-haired triangles) 34 



— Abdomen not unicolorous 36 



34. Mesonotum black; no spot at furcation 35 



— Mesonotum bordered by a band of whitish pile; spot at 

 furcation punctifer Osten Sacken 



35. Eyes with distinct upper area of enlarged facets; a 

 tuft of white hairs beneath scutellum on tergite 1 



kesseli Philip 



— Eyes with upper facets but little differentiated; ab- 

 domen entirely black-haired aegrotus Osten Sacken 



36. Abdomen with a median row of pale spots forming a 

 parallel-sided stripe 37 



— Abdomen not so colored; furcation with a dilute infus- 

 cated spot monoensis Hine 



37. Stump vein present; antennae mostly black 



productus Hine 



— Stump vein absent; antennae pale 



lineola scutellaris Walker 



REFERENCES 



BRENNAN, J. M. 



1935. The Pangoniinae of Nearctic America (Tabanidae, 

 Diptera). Univ. Kansas Sci. Bull., 22:249-401. 

 CAMERON, A. E. 



1926. Bionomics of the Tabanidae (Diptera) of the 

 Canadian Prairie. Bull. Ent. Res., 17:1-42. 

 MARCHAND, W. 



1920. The early stages of Tabanidae (horse-flies). 

 Monogr. Rockefeller Inst. Med. Res., 13:1-203. 

 MIDDLEKAUFF, W. W. 



1950. The horse flies and deer flies of California. Bull. 

 Calif. Insect Surv., 1:1-24. 

 PHILIP, C. B. 



1947. A catalog of the blood-sucking fly family Tabanidae 

 (horseflies and deerflies) of the Nearctic region north 

 of Mexico. Amer. Midi. Nat., 37:257-324. 



449 

 Wirth and Stone: Diptera 



STONE, ALAN 



1930. The bionomics of some Tabanidae (Diptera). Ann. 



Ent. Soc. Amer., 23:261-304. 

 1938. The horseflies of the subfamily Tabaninae of the 

 Nearctic region. U.S.D.A. Misc. Publ., 305:1-171. 

 WEBB, J. L., and H. W. WELLS 



1924. Horseflies: biologies and relation to western 

 agriculture. U.S.D.A. Bull. 1218, 35 pp. 



Family DOLICHOPODID AE 



The small, usually metallic blue or green "long- 

 legged flies" of the family Dolichopodidae are seen 

 everywhere, especially where patches of sunlight 

 play on damp, shaded, heavily vegetated areas. The 

 family is a large one, and the biology is in general 

 so little known that one cannot yet generalize about 

 the aquatic groups. For this reason only those few 

 genera whose larvae are known to be aquatic are 

 included here, and more complete keys to adults can 

 be found in the list of references cited. The adults 

 share with those of the Empididae the curious habit 

 of mating dances, for which the males very often 

 have striking, specific ornamentations of the antennae, 

 legs, or wings. Sexual dimorphism is often great, and 

 the females of many genera are difficult, if not impos- 

 sible to separate. The larvae as well as the adults of 

 this family are predaceous, and larval habitats range 

 all the way from mud and water (Dolichopus, Argyra, 

 Campsicnemus, and Hydrophorus), moist sandy beaches 

 (Tachytrechus and Hypocharassus), dry sandy beaches 

 (Asyndetus), intertidal rocks (Aphrosylus, Hygro- 

 cele Uhus, Hydrophorus, and Cymatotopus), tree cav- 

 ities (Systenus), and beneath tree bark (Medetera), to 

 mines in the stems of grasses and sedges (Thrypticus 

 and Oligochaetus). 



The larvae of this family can be distinguished by 

 the small, retractile, semimembranous head with a 

 triangular dorsal plate and long, slender, dorsal and 

 tentorial rods extending far back into the body (fig. 

 14:49p,s,0; minute anterior spiracles (fig. 14:49n), 

 the posterior spiracles small (fig. 14:49 g,k,o,x) and 

 borne on the concave caudal end of the body between 

 several unequal pairs of short lobes (fig. H'A9b,e,g, 

 i,n,y). The pupae (fig. U:49c,f,j,m,q,u) are usually 

 formed within a cocoon made of pieces of the larval 

 medium cemented together with a silken lining (fig. 

 14:49/, to). The elongate thoracic respiratory organs 

 project far in front of the head through the wall of 

 the cocoon (fig. 14:49a,ic); paired cephalic spines 

 may be present; the leg sacs extend beyond the wing 

 cases; and the abdomen bears transverse bands of 

 spinules. Since the immature stages of very few 

 genera have been sufficiently characterized, the 

 construction of a key is still not practical. Smith 

 (1952) has reviewed what is known of the biology of 

 the immature stages. 



Key to Adults of the North American Genera of 



Aquatic Dolichopodidae 



1. Posterior basitarsus with stout bristles above (fig. 



