The literature on robber fly pupae published primarily since 1972 is reviewed. Terminology used in morphological descriptions of pupal cases is compared and standardized, and some new terminology is used. A general description of asilid pupal cases is presented. Diagnostically useful characters are identified, and a consistent format for descriptions is presented. Pupal cases of 24 species are described for the first time, those of 13 species are redescribed, and additional comments are made on the pupal cases of 12 other species. Keys to species, genera, and higher categories are presented. Asilus lecythus Walker is transferred to the genus Machimus (new combination).

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Recent publications on the immature stages of robber flies (Asilidae) are reviewed and listed for the 14 currently recognized subfamilies (Asilinae, Bathypogoninae, Brachyrhopalinae, Dasypogoninae, Dioctriinae, Laphriinae, Leptogastrinae, Ommatiinae, Phellinae, Stenopogoninae, Stichopogoninae, Tillobromatinae, Trigonomiminae, and Willistonininae). For the Phellinae there are only limited data on the pupal cases, and for the Tillobromatinae there are only limited data on the eggs (potential oviposition site in soil) and pupal cases. The recent literature is compared with pertinent pre-1972 publications.

INTRODUCTIONMany investigators have correlated atmospheric pressure changes with quantitative changes in the daily and seasonal activities of various animals. In particular, the intensity of bird migrations has been correlated with the location of pressure cells and fronts. As early as 1888 Cookeg stated that birds are able to avoid storms by migrating when atmospheric pressure was decreasing. Eaton" observed the greatest spring bird migrations following low pressure centers from the southwest and preceding shower activity.Thomson31 suspected that atmospheric pressure is a stimulus for the initiation of migration, and Clarke* suggested that the stimulus was actually a high pressure cell. Bagg1,2 stated that spring migration in North America is initiated by a barometric pressure gradient falling from east to west. Mascher and Stoltlg made a series of observations in which several variables, including temperature and humidity, were kept constant and demonstrated a weak correlation between nocturnal migratory restlessness (Zugunruhe) and natural variations in atmospheric pressure. However, this correlation was for data grouped into three-and ten-day periods, suggesting a long-term effect.Other investigators have correlated atmospheric pressure changes with the intensity of migrations already underway. Hochbaum15 noted that mass migrations of waterfowl through Manitoba followed an increase in barometric pressure. ProescholdtZ4 stated that the northward migration out of Iowa in the spring was on the western edge of a high pressure system and in the warm sector of a low pressure system. The movement of hawks near Lake Ontario is correlated with a decrease in barometric pressure in association with an approaching low pressure c e l l 3 Nisbet and DruryZ3 conducted a multiple regression analysis of 19 weather variables and showed that songbird and waterbird migrations over Cape Cod, Massachusetts were greatest in the presence of a high pressure cell.Numerous other investigators have also correlated avian migration with changes Landsberg17 suggested that this correlation might occur because migrants utilize tail winds by pressure-pattern-flying, a technique used to gain ground-speed while maintaining a constant air-speed. In 1908 WalteP noted that woodcock in Europe migrated from areas of high pressure to areas of low pressure; this migration pattern could be a reflection of pressure-pattern-flying.The underlying assumption in all of these studies is that birds have the capacity to detect atmospheric pressure changes.We designed and conducted an experiment to determine whether mallard ducks (Anas platyrhynchos) have the ability to detect small atmospheric pressure changes and respond in a prescribed behavioral pattern. in atmospheric p~e~~u~e . 2 -7~1 0~1 4~1 6~~1~2 2~2~2~, 3 2 Supported in part by Biomedical Sciences Support grant no. 31-1801-4511 under NIH grant no. 5 SO5 RR07127-02. 98 Lehner & Dennis: Ducks 99 FIGURE 1. Experimental pressure chamber and electromechanical programming and recording modules. METHODS AND ...

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