378 



Wirth and Stone: Dipt era 



in walking. The variation in size is remarkable, from 

 the 2 mm. wing length of Dasymolophilus to the 

 gigantic Holorusia with wings 40 mm. long. Several 

 genera have the wings more or less reduced, including 

 the snow fly, Chionea, with wings practically absent. 

 Species of this genus are commonly seen crawling 

 around on the snow in winter, but the larvae are ter- 

 restrial in leafmold. Larvae (fig. 14:36) of some 

 species of Tipula known as "leather jackets" often 

 seriously damage meadows and pastures in California 

 by feeding on the roots of the plants. As these larvae 

 come to the surface of the ground at night they can 

 be destroyed by poison baits, and sometimes they 

 are feasted upon by large flocks of birds. The most 

 aquatic genera are Antocha (fig. 14:4/), whose larvae 

 build silken cases, and Hexatoma (fig. 14:4;'). The 

 other species, as far as known, occur at the margins 

 of streams and ponds, either strictly aquatic or in 

 saturated earth, saturated moss cushions, or algal 

 films, on dripping cliff faces, and in similar habitats. 

 The immature stages of very few of the California 

 species have been described so that the keys to the 

 immature stages that follow, adapted from Johannsen 

 (1934), may be quite unsatisfactory for California. 

 The literature is very scattered, and there is no com- 

 prehensive work on the western species. Some of the 

 more important papers dealing with North American 

 species are listed at the end of this section. 



Two nomenclatorial changes should be noted. We 

 use the Meigen 1800 names; hence the genus currently 

 listed as Erioptera is changed to Polymeria. However, 

 by a prior type designation than that usually accepted 

 (see Stone, 1941, p. 413) Erioptera Meigen replaces 

 Molophilus Curtis. 



Keys to the Aquatic or Semiaquatic Genera 

 of North American Tipulidoe 

 Adults 1 



1. Terminal segment of maxillary palpus elongate, whip- 

 lashlike; nasus usually distinct; antenna usually with 

 13 segments; wing with Sci usually atrophied; vein 

 Cu 3 constricted at m-cu, the latter usually at or close 

 to fork of M 3 »«; body size usually large (TIPUL1NAE) 



2 



— Terminal segment of maxillary palpus short; no distinct 

 nasus; antenna usually with 14 or 16 segments; wing 

 with Sc, present, its extreme tip atrophied in some 

 Cylindrotominae; vein Cu, straight, not constricted 

 at m-cu, the latter placed far before the fork of M 3t4 

 usually at or close to fork of M; body size usually 

 small or medium 6 



2. Legs unusually long and filiform; wing with vein Ri, 2 

 atrophied and with Sc 2 ending in Sc close to origin 

 of R. Dolichopeea Curtis 



— Legs of normal stoutness for the family; wing with 

 vein R,,] preserved; when atrophied with Sc of moderate 

 length, Sc, atrophied before fork of Rs and Sc a ending 

 at or near mid-length of Rs (exception, some species 

 of L ongurio); cell second A of normal width 3 



3. Wing with vein R 3 bent strongly caudad before end, 

 thence angularly deflected cephalad, cell R 3 thus 

 being much constricted at or near mid -length 



Holorusia Loew 



10 



11 



12 



13 



14. 

 15 



16. 



17, 

 18. 



Adapted from Alexander, in Curran, 1934. 



Wing with vein R 3 straight or only gently arcuatedl 



throughout its length, not constricting the cell 1 



Flagellar segments without verticils, the lower face 

 of individual segments produced to give the organ 

 a serrate appearance; terminal flagellar segment 



abruptly more slender Prionocera Loew 



Flagellar segments verticillate, simple or nearly so 



5 



Abdomen of both sexes greatly elongated, somewhat 

 resembling that of a dragonfly; verticils of outer 

 flagellar segments very long and conspicuous; valves 

 (cerci) of ovipositor with smooth margins 



L ongurio Loew 



Abdomen not so elongated or valves with serrate 

 margins; antennal verticils of moderate length only 



Tipula Linnaeus 



Wing with tip of R lt2 atrophied, giving the appearance 

 of a long fusion back from margin of veins R, and 

 anterior branch of Rs; free tip of Sc 2 preserved (CY- 

 LINDROTOMINAE) 7 



Wing sometimes with tip of R,» 2 atrophied but not giving 

 the appearance of a long fusion backward from margin 

 of veins R, and anterior branch of Rs; free tip of Sc, 

 preserved in many species of the tribe Limoniini, 



lacking in other tribes (LIMONIINAE) 8 



Head and intervals of mesonotal praescutum with 

 numerous deep punctures; a deep median groove on 



praescutum Triogma Schiner 



Head and intervals of mesonotal praescutum smooth; 

 no median praescutal groove .... Phalacrocera Schiner 

 Eyes hairy; wing with vein Sc, very long, Sc a lying 



basad of origin of Rs 9 



Eyes glabrous; wing with Sc t short or of moderate 

 length; when long Sc 2 lying distad of origin of Rs; 

 where Sc 2 lies basad of origin of Rs the entire vein 



Sc is shortened 10 



Antenna usually with 16 segments; size large, wing 



usually more than 10 mm Pedicia Latirelle 



Antenna usually with 13 or 14 segments; size small, 

 wing usually less than 8 mm. . . . Dicranota Zetterstedt 

 Wing with free tip of Sc 2 often present; veins R 4 and 

 R 5 fused to margin, only 2 branches of Rs being present; 



Antenna usually with 14 or 16 segments 30 



Wing with free tip of Sc 2 atrophied; veins R 4 and R s 

 separate, the former usually transferred to the upper 

 branch, R a * 3 , to form a distinct element R, t3 , 4 ; usually 

 with 3 branches of Rs present; antenna usually with 



16 segments 11 



Tibial spurs present 12 



Tibial spurs lacking 21 



Antenna with not more than 12 segments 



Hexatoma Latreille 



Antenna with more than 14 segments 13 



Apical cells of wing with macrotrichia 14 



Cells of wing without macrotrichia (excepting in 



stigmal area) 17 



A supernumerary cross vein in cell M 



Limnophila (in part) 



No supernumerary cross vein in cell M 15 



Cell R 3 of wing sessile, subsessile or short-petiolate; 



Rj* 3t4 lacking or much shorter than m-cu 1G 



Cell R 3 of wing long-petiolate, R 1( . 3 » 4 being as long as 



or longer tham m-cu Parade Iphomyia Alexander 



Wing with macrotrichia abundant, involving the cells 



basad of cord Ulomorpha Osten Sacken 



Wing with sparse macrotrichia in cells beyond cord 



only Limnophila (in part) 



Wing with vein R 2 lacking; m-cu at outer end of cell 



1st M a Phyllolabis Osten Sacken 



Wing with vein R 2 present; m-cu at or before V 3 the 

 length of cell first M 2 when the latter is present .... 18 

 Wing with m-cu at or close to fork of M; anterior arculus 



lacking Dactylolabis Osten Sacken 



Wing with m-cu beyond the fork of M, at from "J to about 

 l / 2 the length of cell first M 2 ; where close to fork of M 

 the arculus complete 19 



