CALIFORNIA WASPS of the GENUS OXYBELUS (Hymenoptera: Sphecidae, Crabroninae)
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Dorsal view of Oxybelus califwnicum Bohart and Schlinger, female. BULLETIN OF THE CALIFORNIA INSECT SURVEY VOLUME 4, NO. 4 CALIFORNIA WASPS OF THE GENUS OXYBELUS (Hymenoptera: Sphecidae, Crabroninae) BY RICHARD M. BOHART and EVERT I. SCHLINGER (Department of Entomology and Parasitology, University of California, Davis) UNIVERSITY OF CALIFORNIA PRESS BERKELEY AND LOS ANGELES 1957 BULLETIN OF THE CALIFORNIA INSECT SURVEY Editors: E. G. Linsley, S. B. Freeborn, P. D. Hurd, R. L. Usinger Volume 4, No. 4, pp. 103-142, plates 9-16, 23 maps, frontis. Submitted by Editors, May 29, 1956 Issued April 11, 1957 Price, 75 cents UNIVERSITY OF CALIFORNIA PRESS BERKELEY AND LCS ANGELES CALIFORNIA CAMBRlDGE UNIVERSITY PRESS LONDON, ENGLAND PRINTED BY OFFSET IN THE UNITED STATES OF AMERICA CALIFORNIA WASPS OF THE GENUS OXYBELUS (Hymenoptera, Sphe cidae, Cr abroninae) BY Richard M. Bohart and Evert I. Schlinger INTRODUCTION The winglike expansions of the postscutellum and Generally speaking, the species of Oxybelus the spear-shaped median spine of the propodeum in can be considered rare. That is to say, they are species of the genus Oxybelus have always often local, most of them are small, their habits seemed remarkable to entomologists who have are inconspicuous, and ordinary collecting meth- observed them. It is surprising that with about 50 ods yield only occasional specimens. We have species known from this continent, only seventeen seen entire collections from twenty-five of the workers have published taxonomic studies other major entomological museums in the country, and than catalogues on the North American members some of these contained only a dozen or so since Thomas Say described the first species in specimens. The material examined has totaled 1824. Those who followed Say, listed in approxi- about 5,000 specimens of which some 2,000 are in mate chronological order, were E. T. Cresson, collections of the University of California. At A. S. Packard, Abbk Provancher, C. H. Robertson, least one-half of the total has involved the 3 P. Cameron, W. J. Fox, T. D. A. Cockerell, C. F. relatively common species, emarginatum, uni- Baker, H. L. Viereck, H. S. Smith, S. A. Rohwer, glumis quadrinotatum, and califonzicum. From the C. E. Mickel, N. Banks, V. S. L. Pate, K. V. standpoint of distribution records, at least, there Krombein, and the writers. Of the early papers is a great need for further collecting of these in- those of Robertson were outstanding. His key sects in all parts of North America. (1889) to the known species was expanded by Smith (1908) and by Mickel (1918), but all three keys were fragmentary in the light of the presently BIOLOGY known fauna. The only important contributions at the generic For the large number of known Oxybeline species, level were those of Pate (1937, 1940) who added a our biological information is scarce. To our third genus, Enchemicrum, to ow fauna, and who knowledge no complete biology of any species has discussed relationships of the Oxybelini from a been published, although numerous notes are world standpoint. available dating from the early nineteenth cen- Burks (1951) was the first since Dalla Torre tury. Many European authors have contributed to (1897) to assemble a check list which incorporated ow knowledge of these wasps, and for an account previously published synonymy. In this list of 65 of the bibliographical and prey records of the species and subspecies from America north of European species, see Berland (1925). Among Mexico, only 9 species were recorded from Cali- North American writers, Peckham (1898), Parker fornia. One of these, laetum Say, was based on a (1915)’ and Williams (1936) have recorded most of misidentification. Subsequent to Burks’ list, the data, all of which pertains to one subspecies, further synonymy was added by Krombein (1955) Oxybelus uniglumis quadrino tatum. and an extensively revised synonymic list was The Oxybelus wasps are solitary, each female given by Bohart and Schlinger (1956~). In the constructing and provisioning her own nest or latter list 50 of the 96 names pertaining to species nests, usually in sandy areas. The nest is short, and subspecies of Oxybelur in North America were straight, and consists of one or rarely, two cells. retained as valid. In the present study we have It is not lined with foreign material but is simply attempted to differentiate 42 species and sub- dug out of the sand by the forelegs of the female. species which we have been able to recognize The cell is terminal, provisioned with several from United States and Mexico. Included are 24 flies whose number depends on the size of the from California, and 5 of these-cocopa, kmm- individual prey, and the egg is laid on the first beini, I insl eyi* macswaini, and timbedakei- ap prey member of the cell. The larva emerges in pear to be endemic forms. about a day, devours its stored food, prows and 104 BULLETIN OF THE CALIFORNIA INSECT SURVEY pupates in ten to fifteen days, and emerges some species in the Society Islands. In North America two to three weeks later. There are one or two about 50 species and subspecies are known to generations each year, possibly even three in a occur. The majority of these are found west of the very favorable environment. The female of quad- Mississippi River, and many of them have a dis- rinotatum impales her prey on her sting and carries tribution extending from the Great Plains west it in this manner while flying. This also frees into California and south into northern Mexico. We her legs for walking. The prey is held head first, recognize 24 species as Californian, and of these, sometimes upside down, so that most of it extends 19 range more or less broadly to the East. On the beyond the abdomen of the wasp. This subspecies other hand, this leaves 5, or the respectable reopens her nest on each arrival with prey and figure of 20.8 per cent, as apparently endemic closes it before each excursion. The European forms. In addition to the 24, 5 other species have species, 0. quattuordecimnotatum Olivier, differs been collected as far west as Arizona and may somewhat in its biology in that the prey is held eventually be found in California. These are under the body by the hind pair of legs rather than crandall i, p aracoc h i se, spari deum, subcornu t um. on the sting. and taenigaster. Only 2 of the 5 genera of Oxybelines have It appears likely that the American species may known prey records; Oxybelus, which use flies, have evolved from some member of the uniglumis and Belomictus, which use flower beetles and group, which is dominant in Europe. However, if mirids. Flies of the following families and genera our Oxybelus entered by the traditional Northwest have been recorded as prey of our North American Passage, they were able to adapt themselves to Oxybelus: Anthomyidae (Hylemyia), Calliphoridae the arid regions of the West and developed into a (Lucilia), Chloropidae (Thaumatomyia), Lonchaei- number of species groups. These are quite dis- dae (Lonchaea), Muscidae (Musca), Sarcophagidae tinct from any found elsewhere, and all but one are (Sarcophaga), Stratiomyidae (Micmchrysa), Syrphi- represented in California. Because of the predom- dae (Allograpta), and Therevidae (Thereua). The inance of species of the emaginatum group in European species of Oxybelus have been cited Central and South America, it is possible that also as using most of the above families, and in these developed from early isolations and re- addition various genera of Dolichopodidae, migrated north into the United States in relatively Ephydridae, Lauxanidae, Sapromyzidae, Scope- recent geological times. umatidae, and Tachinidae have been observed. At present there appears to be only a single Many of the flies recorded as prey are of eco- truly Holarctic species, uniglumis. The other one nomic concern, such as Musca dornestica L., M. occurring on both continents, bipunctatum, was crassirostris Stein, and species of the root mag- supposedly introduced into eastern United States got genus, Hylemyia. Requaert, as noted by Pate about 1935 according to Pate (1943). (1937:375), explained that adults of Oxybelus The whole genus shows a predilection for dry pytura (Rohwer) are called ?policias? by natives areas, and the majority of North American species of Guatemala because of their beneficial attack on are essentially creatures of the Austral life zone. adults of Simulium species, some of which are In California, 18 of the known species are pri- vectors of onchocerciasis. Also, several authors marily Sonoran (Austral) in distribution, 4 are have recorded Oxybelus rufipes Taschenberg principally Transition, and 2 are rather extensively as a predator on tsetse flies in Africa. Therefore Au stro-boreal. it seems that some economic benefit may result Distribution maps show the known localities from Oxybelus species near places of habitation (by the use of dots) and the probable geographic as well as in agricultural areas. distribution (by the use of overlays) for all the During our studies on Oxybelus, numerous California species. The range of each species, as flower (nectar) hosts have been encountered indicated by the overlay, is limited by a solid through observations, specimen data, and the line where enough information is available, and literature. Apparently the species are not directly by a dashed line where the range is somewhat associated with the flower hosts involved, but are doubtful. rather found feeding from whatever attractive Besides the actual locality records of the plants happen to be in flower. Thus, the impor- specimens, the following works were consulted in tance of botanical records seems questionable. determining the distributional limits of our species: Merriam?s Life Zones (1898), Dice?s Biotic Pmuinces (1943), Map of the Faunal Zones DISTRIBUTION of America North of Mexico, in Muesebeck et al.