BULLETIN OF THE CALIFORNIA INSECT SURVEY VOLUME 6, NO. 5 THE SOLDIER FLIES OR STRATIOMYIDAE OF CALIFORNIA BY MAURICE T. JAMES (Department of Zoology,State College of Washington, Pullman) UNIVERSITY OF CALIFORNIA PRESS BERKELEY AND LOS ANGELES 1960 BULLETIN OF THE CALIFORNIA INSECT SURVEY Editors: E. G. Linsley, S. B. Freeborn, P. D. Hurd, R. L. Usinger Volume 6, No. 5, Pp. 79-122, plates 6-10, 19 maps Submitted by editors, October 14, 1958 Issued April 22, 1960 Price, $1.00 UNIVERSITY OF CALIFORNIA PRESS BERKELEY AND LOS ANGELES CALIFORNIA CAMBRIDGE UNIVERSITY PRESS LONDON, ENGLAND PRINTED BY OFFSET IN THE UNITED STATES OF AMERICA TO THE MEMORY OF MY SON TED THE SOLDIER FLIES OR STRATIOMYIDAE OF CALIFORNIA BY MAURICE T. JAMES To date, no publication has presented a com- forms extralimital to the California fauna). prehensive survey of the Stratiomyidae of the Although of limited economic importance, Pacific coast; the nearest approach to one is the Stratiomyidae are more significant from the the study of the aquatic forms by Wirth and theoretical standpoint than is usually recog- Stone (1956). Even this work falls a little nized. Indeed, if this family had become ex- short of its expected goal since two groups tinct in prehistoric times, some valuable links have had to be omitted. These are the in the evolutionary development of Diptera Pa chyga s t rina e and the E upar yph us-Aoc hlet us would have been lost to science. Nowhere complex which are being studied by Dr. Ken- within a closely knit taxonomic group can be neth J. Kraft and Dr. John A. Quist. It is hoped found a better example of evolutionary change that a supplement to this pager can include involving a major structurethan in the stratiomyid these two groups. antenna, which we can trace from the relatively The Stratiomyidae are placed, together with primitive, undifferentiated l-segmented (e.g., the Tabanidae, Coenomyiidae, Pantophthalmidae, Cyphomyia) and the somewhat reduced but still and Erinnidae, near the base of the Brachycera. undifferentiated 7- to 8-segmented (e.g., In all these flies the empodia are pulvilliform; Stratiornys), through the stylate (e.g., Eulalia, venation is of a relatively primitive type; and some Adoiomyia), attenuatestylate (e.g., some the antenna, although in some groups it may be Adoxomyia, Nemotelus), and terminally aristate aristate, has the basal complex distinctly an- (Acrochaeta), to the subterminally aristate form nulated (Steyskal, 1953). In the Stratiomyidae (e.g., Sargus). Much of that development can venation is quite primitive although the veins be seen within a single tribe, the Myxosargini are crowded toward the costal margin, and (James, 1942). Though the final development there is a strong tendency toward reduction, for of the dorsally aristate, pendant antenna, with example, in the weakening or loss of R,, M,, M, its thoroughly consolidated basal flagellar com- and cross veins r-m and in-cu, and in the gen- plex comes later, this is certainly a marked eral weakening of the veins surrounding the development to take place in one family. discal cell. A venational character that dis- The sidewise, rather than direct, develop- tinguishes the Stratiomyidae from the Erinnidae ment of a characteristic venational pattern has and Coenomyiidae is the origin of the radial obscured some phylogenetically more important sector at or near the base of the discal cell wing developments. It is not the Beridinae and rather than far before it. Among other charac- Chiromyzinae, commonly considered the most ters, we might mention the frequently spinose primitive subfamilies, which have the most condition of the scutellum (a character which primitive venation but, on the other hand, the suggested to Bauer the name Notacantha for Cyphomyiinae. From this subfamily, progres- the Stratiomyidae and their close relatives), sive reduction and weakening of venation can and the lack of tibial spurs (except in some be traced in three directions, through the BO BULLETIN OF THE CALIFORNIA INSECT SURVEY Stratiomyinae, Potamidinae, and to a lesser The stratiomyid fauna of California seems to extent, the Sarginae,. culminating in such consist of three chief elements: the introduced genera as Oplodontha, Nemotelus, and typical (from Europe, South America, or Australia), Micrachrysa, respectively. An independent the more widespread Nearctic species that branch which, at least so far as venation is have spread into the state, and the endemic. concerned, must have originated below the The introduced species are found exclusively Cyphomyiinae, leads through the Cbiromyainae in the Sarginae, Chiromyzinae, and Hermetiinae and Beridinae to the otherwise highly special- and are either sod feeders or scavengers, both ized Pachygastrinae. easily spread by commerce. It is not easy to Another bit of significant phylogenetic de- separate the endemic forms from the more wide- velopment that takes place within the family spread ones that have entered the state, but is the differentiation of the pre and postabdo- many cases are quite clear. A number of the men. The whole process can be demonstrated latter category, it will be noticed, have just in the Chiromyzinae and the Beridinae, where barely reached California. reduction and telescoping of segments VI through VIII takes place gradually. Even some of the sidewise developments have interesting aspects aside from their own The collecting data presented herein repre- peculiarities. The vestigial mouth parts of the sent the accumulation of more than a quarter Chiromyzinae are, of course, adaptive, but a century, although records were relatively mea- similar situation occurs independently in sev- ger until the work of the California Insect Sur- eral groups of the higher Diptera. The develop- vey got under way. Many collections which ment of the subscutellum (metascutellum), have been examined during this period are ?not which Curran (1924) considered a phylogenetic acknowledged here, but those from which speci- link between the Stratiomyidae, Syrphidae, and fically cited records have been drawp, with the Larvaevoridae, falls in the same category; pertinent abbreviations, are as follows: likewise the spinose scutellum which is again Institutional collections: California Insect encountered, for example, in the Diopsidae. Survey, University of California, Berkeley However, a special significance of this char- (C.I.S.); University of California, Davis (U.C. acter in the Stratiomyidae is that, once de- D.); University of California, Los Angeles veloped, the spines tend gradually to disap- (U.C.L.A.); University of California, River- pear (e.g., Strutiomys through various species side (U.C.R.); California Academy of Sciences of Labostigminu). (C.A.S.); California Department of Agriculture (C.D.A.); American Museum of Natural History Larval habits and habitats are not as varied (A.M.N.H.); United States National Museum as might be expected. The Cyphomyiinae, so (U.S.N.M.); Ohio State University (O.S.U.); far as known, are scavengers in decaying plant University of Arizona (U.A.); Brigham Young materials, a habit that is carried through the University (B.Y.U.); University of Kansas Hermetiinae and the Sarginae although both (K.U.); State College of Washington (W.S.C.). these families tend strongly .toward coprophagy Individual cdlections: George E. Bohart and, possibly in part, predatism. The phyto- (G.E.B.); Mont A. Cazier (M.A.C.); Gerald F. saprophagous habit is found also in some Pota- Kraft (G.F.K.); Joe Schuh (J.S.); R. M. Bohart midinae, thoush this subfamily, as well as the (R.M.B.); Paul H. Arnaud (P.H.A.); Stanley W. Stratiomyinae, becomes essentially aquatic, Bromley (S.W.B.), now part of the United where the saprophagous habit may be main- States National Museum collection; R. H. tained or may change to phpophage or micro- Painter (R.H.P.); Maurice T. James (M.T. J.). predatism. The chiromyzine- beridine-pachy- I express my appreciation to the individuals gastrine .stem also begins trophically in phyto- and curators of the collections above mentioned phagy and phytosaprophagy and continues, and to others not acknowledged here, who have although some Pachygastrinae become pre- from time to time loaned me materials from daceous on bark beetle larvae (and consequent- which pertinent records have been taken. I also ly somewhat beneficial to man). The aquatic express my appreciation to Miss Patricia Pack- habitat, though shared by many members of the ard who prepared the original illustrations, and family, seems to be a secondary development; to my son, Ted, who was helping me in the nevertheless, it is significant that no habitat is preparation of this manuscript when tragedy very far removed ecologically from the aquatic. intervened. THE SOLDIER FLIES OF CALIFORNIA 81 In preparing the keys, particularly the one arising from the discal cell ......Beris% to subfamilies and genera, I have had in mind Abdomen with five principal segments; body the California fauna in particular. Generalities robust, the abdomen conspicuously broader .have often been sacrificed to utility. Conse- than the thorax; four strong veins arising ‘quently, the generic key will fail to work for from the discal cell ........Exodontha 3( some of the extralimital species of genera in- 4.c”~rossvein m-cu present, .......... 5 cluded, even for the eastern United States, and Cross vein mcu absent, part of vein Cu, for some extralimital genera of the subfamilies. consequently forming part of the lower mar- On the other hand, I hope that the construction gin of the discal cell 12 of these keys along these lines will lead to ............ easier and more positive identification of the 5. Antenna with or without a more or less California forms and others that might be ex- well-defined thickened style but without pected to occur within the limits of the state or an arista (subfamily Stratiomyinae) ....G in closely adjacent areas. Antenna with a distinct subterminal arista One North American subfamily, the Cypho- (subfamily Sarginae) ...........