Vol. 89, Nos. 5 & 6, May & June 1978 117 SCANNING ELECTRON MICROSCOPY OF ULTRAVIOLET-REFLECTIVE PRUINOSITY IN SPECIES OF OCHTHERA (DIPTERA: EPHYDRIDAE)' B,A. Steinly,^ D.L. Deonier,^ J.T. Regensburg"* ABSTRACT: The micro-structural characteristics of the ultraviolet-reflective pruinosity on Ochthera were studied with a Coates and Welter Model 106 field emission scanning electron microscope. Micrographs of pruinosity having the greatest ultraviolet reflectance on Ochthera mantis (De Geer) and O. lauta Wheeler showed it to be composed of flattened units somewhat concave in cross-section and abruptly deflected apically. Nonreflective or minimally reflective pruinosity in both species was shown to be composed of appressed subuliform units or, as on dark areas of the abdomen, short, decumbent, setuloid units. The scanning electron microscopy of cuticular surfaces of acalyptrate Diptera has been largely neglected. Bauchhenss and Renner (1977) investi-gated the pulvillus of Calliphora erythrocephala (Diptera: Calliphoridae) and Shfer and Sekhon (1964) the fine structure of the sense organs on the antennal flagellum oi Sarcophaga argyrostoma (Diptera: Sarcophagidae). The present study was initiated to provide more information on pruinosity of acalyptrates and to determine the micro-structural characteristics of ultraviolet-reflective pruinosity on Ochthera (Diptera: Ephydridae). When photographed through a Wratten filter, the golden pruinose face and silvery pruinose front coxae of O. mantis were shown to reflect relatively much more ultraviolet radiation than other body regions (Deonier, 1975). These data along with observed semaphoring with the large raptorial front legs and experimental disruption of mating in sexual pairs by obUteration of reflective fore-coxal pruinosity were interpreted as evidence for a signalling function of the reflectance. Materials and Methods The 12 specimens of Ochthera mantis examined were collected at Ravenel L., Highlands, Macon Co., North Carolina; a tributary of Four-mile Cr., Preble Co., Ohio; and near Oxford, Butler Co., Ohio. The 4 specimens of O. lauta were collected in Kansas at Sappa L., Decatur Co. and the Kansas R. near Accepted for publication: February 9, 1978 2 3 4 Department of Zoology, Miami University, Oxford, OH 45056 ENT. NEWS, 89, 5 & 6: 117-124, May & June 1978 \ JUN 3 'i978
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