PROC. ENTOMOL. SOC. WASH. 87(1), 1985, pp. 94-97 A KEY TO NYMPHS OF FOUR SPECIES OF THE GENUS PODISUS {HEMIPTERA: PENTATOMIDAE) OF NORTHEASTERN NORTH AMERICA Edward W. Evans Division of Biology, Kansas State University, Manhattan, Kansas 66506. Abstract. — A simple key based on color characters is provided for nymphs of Podisus maculiYcntns (Say), P. iiiodestus (Dallas), P. placidus Uhler, and P. sene-ventris Uhler. Five species of the genus Podisus occur in northeastern North America. Of these, four species (Z'. rnacii/ivcntris (Say), P. niodestus (DaWas). P. placiditsUMer. and P. scricYcntns Uhler) are commonly collected (e.g.. Kirkland. 1898; Tosto-waryk, 1971; Morris, 1972; Evans, 1982, 1983). The fifth species, P. fret us Olsen. is an especially large (adult length: 12.5-14 mm) and seemingly rare member of the genus that has been reported sporadically from Maine to Florida and west to Indiana and Michigan (McPherson, 1982). Because they are predators that often attack economic pests, these insects arc of considerable interest to many ento-mologists. At present, however, reporting of these insects' habits is hampered by inability to identify nymphs encountered in the field. Therefore I have developed the following simple key for nymphs of all but P. frclus (with which I am un-familiar). Adults arc well treated by several published keys (e.g. Torre-Bueno. 1939; Furth, 1974; McPherson. 1982), and a key to eggs of these four species is given by Coppel and Jones (1962). Because nymphs of the four species are essentially indistinguishable in structural characters, the key given below is based on differences in color pattern among the species. These differences are readily apparent in freshly collected or frozen ma-terial. The colors fade slowly when specimens are stored in alcohol, but fading can targely be prevented if specimens preserved in alcohol are kept refrigerated. The key is based on nymphs that I reared from eggs laid by adults collected near Ithaca, New York. Voucher specimens of adults of the four species have been placed in the Cornell University Insect Collection under Lot 1086. Extensive collections and subsequent rearings of Podisus nymphs have proved the key to be reliable. Detailed descriptions of the nymphs of three of the species are available elsewhere: P. scricvcntris (Prebble. 1933), P. niacullventris (DeCoursey and Es-selbaugh, 1962). and P. placidus (Getting and Yonke, 1971). The terms used in the key are identified for a fourth instar nymph of Podisus in Fig. 1 . One can confirm that an unidentified nymph belongs to the Pentatomidae by using the key provided by Herring and Ashlock (1971). One must know also that indeed the specimen belongs to the genus Podisus before using the key given
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