Great Basin Naturalist Volume 38 Number 1 Article 8 3-31-1978 Observations on the prey and nests of seven species of Cerceris (Hymenoptera: Sphecidae) Howard E. Evans Colorado State University, Fort Collins William L. Rubink Colorado State University, Fort Collins Follow this and additional works at: https://scholarsarchive.byu.edu/gbn Recommended Citation Evans, Howard E. and Rubink, William L. (1978) "Observations on the prey and nests of seven species of Cerceris (Hymenoptera: Sphecidae)," Great Basin Naturalist: Vol. 38 : No. 1 , Article 8. Available at: https://scholarsarchive.byu.edu/gbn/vol38/iss1/8 This Article is brought to you for free and open access by the Western North American Naturalist Publications at BYU ScholarsArchive. It has been accepted for inclusion in Great Basin Naturalist by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. OBSERVATIONS ON THE PREY AND NESTS OF SEVEN SPECIES OF CERCERIS (HYMENOPTERA: SPHECIDAE)' Howard E. Evans^ and William L. Rubink^ Abstract.— Cerceris species are remarkably constant in their prey preferences. Records are presented from di- verse localities that confirm prey constancy in five species. An apparent exception is noted in the case of C. crotonella Viereck & Cockerell. A mixed aggregation of C. fiimipennis Say and C. californica Cresson is reported, both preying upon Buprestidae and using some of the same species. Nest and prey of C. conifrons Mickel are re- ported for the first time. One of the striking features of the behav- an arroyo 30 km NE of Lordsburg, New ior of species of Cerceris is their prey con- Mexico. The prey proved to be a tenebrio- stancy. Even in widely disparate parts of nid beetle, Pechalius siibvittatus Casey. On the range, females of a given species tend 24 and 31 August 1976, we studied an ag- to utilize beetles of only one family, often gregation of some 40 females of this species of only a few related genera. Such special- about 9 km N of Roggen, Weld Co., Colo- ization doubtless reduces competition rado. At this site a single species of Te- among species nesting together. Evans nebrionidae was being employed as prey, (1971) reported three species nesting togeth- Bothrotes phimbeus plumbeus (LeConte) er at Bedford, Massachusetts, each preying (N = 38, with several additional sight records upon quite a different kind of weevil; later and several additional records from the (1974) he added still a fourth species from same area in 1977). Since Alcock (1974, this same site, utilizing still a different kind 1975) has published two excellent papers on of weevil. Despite their prey specificity, the C. simplex macrosticta, we present only a species of Cerceris are remarkably similar in few notes here. The prey at Alcock's site in many aspects of their nesting behavior. Arizona also consisted of a single species of In this paper we report still further ex- Tenebrionidae, in this case Metapoloba amples of prey constancy in diverse parts of pruinosa (Horn) (N = 60, with additional the ranges of five species. We also report sight records). It is interesting that these an apparent exception in the case of one three genera, Metapoloba, Bothrotes, and species, C. crotonella Viereck & Cockerell. Pechalius, all belong to the tribe Epitragini. Further, we report a mixed aggregation of Lin (1967) studied C. simplex graphica two closely related species, C. fiimipennis Smith in Oklahoma and found the prey Say and C. californica Cresson, both prey- there to consist of a single tenebrionid spe- ing upon Buprestidae, including several of cies, Eleodes opaca (Say), a member of a the same species. The first records of the different subfamily. Since the ranges of nest and prey of C. conifrons Mickel are these two subspecies of simplex appear to presented, as well as diverse notes on the overlap broadly, thought might be given to nests of other species. the possibility of their being separate spe- cies. site, nests were located in Cerceris simplex macrosticta At the Roggen Viereck & Cockerell a steep slope of fine-grained sand, mostly devoid of vegetation, where the chief asso- On 20 July 1976, we took a female of ciates were species of Bembix, Microbembex, this large species flying with her prey over and at least two species of bees. Cerceris 'Research supported by the National Science Foundation, grant BNS76-09319. 'Department of Zoology and Entomology, Colorado State University, Fort Collins, Colorado 80523. 59 60 Great Basin Naturalist Vol. 38, No. 1 nests were situated over a distance of some and we present only a few notes confirming 30-40 m along the bank, but they were def- prey constancy in diverse parts of the initely clumped in certain places, along range. On 23 July 1975 we took a female with those of the bees. In these clumps nest C. hicornuta hicornuta 14 km W of La- entrances were often no more than 5-15 cm porte, Colorado, carrying a weevil, Spheno- apart, but the clumps themselves were sepa- phorus cicatristriatiis Fahraeus in her man- rated by several meters. Nest entrances dibles. She landed on a dirt road, were left open while the females were pro- apparently en route to her nest, and rested visioning, and each was surrounded by a there for a moment with her wings extend- rim of sand, as is usual in this genus. A ed obliquely above her abdomen. male macrosticta was taken on flowers of During the month of July 1976 we ob- Croton texensis (Klotzsch) not far away, but served an aggregation of C. hicornuta fidelis no males were seen in the nesting area. Viereck & Cockerell at the Lajoya Wildlife During the morning hours, females were Preserve, 30 km N of Socorro, New Mexico. frequently seen descending to their nests On 1 July we counted 44 nests in an area 3 holding beetles in their mandibles in such a X 5 m in flat, hard-packed sandy loam be- way that they hung down obliquely from side a dirt road. About an equal number of the body. Tliey were frequently followed by Tachijtes aurulentus (F.) also nested here, 1-3 satellite flies, Senotainio sp., and when and the nests of the two species were some- so followed the wasps would often circle what intermingled and rather similar in ex- widely before entering their nests, making ternal appearance, both having a large loops several meters in diameter at different mound at the entrance and the hole near heights and occasionally landing on vegeta- the center of the mound. However, the tion. One female spent six minutes making Tachytes were most active in the early an evasive flight of this nature, then finally morning, as early as 0630, while the Cer- entered the nest without any flies following ceris provisioned their nests over the warm her. Only 1 of the 12 cells eventually exca- part of the day. The Cerceris nests were vated appeared to have had the contents well spaced, mostly 0.3-1.0 m apart, but destroyed by maggots, so we judge that the some were very close to Tachytes nests (in wasps are often successful in evading satel- one case only 15 cm from a Tachytes nest). lite flies. Provisioning females entered the area 1-2 Nest structure agreed closely with that m high and plunged directly into the open figured by Alcock (1974) for this species. nest entrances. Prey was carried in the One of the two nests we excavated had five mandibles as usual in the genus, and con- cells, the other seven. Cells varied in depth sisted of a single species of weevil, Spheno- from 17 to 32 cm (x = 26, precisely the phorus austraUs Chittenden (N = 12). Wee- same figure Alcock obtained in Arizona). In vils were stored in the burrow, as usual in both cases beetles had been stored at vari- this genus. We dug out only one nest in ous points in the burrow, chiefly near its 1976, early in the season and apparently be- terminus. The number of beetles per cell fore any cells had been made. The nest had was two in one case, three in nine cases, a mound at the entrance measuring 15 x 17 and seven in one case. Most cells measured cm, 2.5 cm high, with the burrow pene- 10 x 12 mm, but the one containing seven trating the center. Burrow diameter was 8 beetles measured 14 x 23 mm. We suspect mm. This burrow was vertical for 29 cm, this was a "female producing cell", the oth- then leveled off abruptly and extended an- ers "male" cells, a situation that is probably other 27 cm before terminating blindly. common if not universal in Cerceris. These Three weevils were found about midway in figures are also very similar to those ob- the horizontal part of the burrow. tained by Alcock in Arizona. In July 1977, we made further observa- tions on this same aggregation, though many fewer nests were visible. Three nests Cerceris hicornuta Guerin were excavated. The first, on 8 July, yielded This is a relatively well-studied species. five weevil prey from the single, recently March 1978 Evans, Rubink: Gerceris Wasp Nests 61 completed cell. Two species, Sphenophortis prey 4 km S of Caddoa, Bent Co., Colo- neomexicanus Chittenden (N = 4) and S. ci- rado. The beetle proved to be Pachijbrachys catristriatiis Fahraeus (N = 1) were repre- minor Bowditch (Chrysomelidae). This is in sented. A second nest, excavated on 12 July, contrast to a record from western Texas of contained no cells and a single weevil, S. ci- this species preying upon a beetle of the catristriatus, midway down the 25 cm long imrelated family Nitidulidae (Evans 1971).