PROC. ENTOMOL. SOC. WASH. 107(3). 2005. pp. 693-699 ALDERFLY (NEUROPTERA: SIALIDAE) FLIGHT PERIODS, SEX RATIOS, AND HABITAT USE IN A VIRGINIA FRESHWATER TIDAL MARSH, LOW FOREST, AND THEIR ECOTONES Edward M. Barrows, Anne M. McIntyre, and Oliver S. Flint, Jr. (EMB, AMM) Laboratory of Entomology and Biodiversity, Department of Biology, Reiss Building Suite 406, Georgetown University, Box 571229, Washington. D.C. 20057-1229, U.S.A. (e-mail:
[email protected]); (OSF) Department of Entomology, Smithsonian Institution, Washington, D.C. 20013-7012, U.S.A. (e-mail:
[email protected]) Abstract. — Six Malaise traps, run from April 1998 through December 1999, obtained 3306 adult Sialis tola Ross (34% females) and one male S. mohri Ross in Dyke Marsh Preserve (DMP), Virginia. They flew from early April through early June. The abundance of S. iola significantly varied among a low forest, freshwater tidal marsh, and the forest-marsh ecotone, sometimes being significantly more common in the ecotone than other habitats. Malaise traps can be used efficiently to survey and monitor sialids in DMP and similar places. A thorough monitoring effort in the Preserve should include at least two traps in the three habitats and monitoring throughout sialid flight periods and the Preserve. Key Words: Neuroptera, Sialidae, alderflies, flight periods, sex ratios, freshwater marsh, low forest This study concerns sialids (Neuroptera: Sialidae, Alderflies) in a freshwater tidal marsh and adjacent low forest in the Mid-Atlantic region of the U.S.A. We provide information about adult sialid abundances and flight periods in three main habitats of Dyke Marsh Preserve (DMP), Virginia — low forest, freshwater tidal marsh, and the ecotone between them, based on Malaise-trap samples. The National Park Service (NPS) requires information on DMP spe-cies, their abundances, and their habitat uses, in order to manage the Preserve prop-erly. A sialid study is particularly crucial at this time because Virginia may use a pes-ticide to control mosquitoes that carry the West Nile Virus. Such mosquito control could have marked deleterious effects on many DMP organisms. Sialids can be abundant in aquatic and adjacent habitats where they are predators of other arthropods and food for vertebrates and other organisms including fish (Azam and Anderson 1969). Bowlker ( 1747) wrote in The Art of Angling, "the Orle Fly ... is the best Fly to Fish with after the May Flyes are gone" (reference in the Oxford English Dictionary 1971). "Orlc"" is an old name for "alder" There are 24 North American sialid spe-cies. Females lay egg masses of U\m^ about 200 through 900 eggs on objects o\ cr w ater such as bridges, culverts, and \egetation (Azam and Anderson 1969. Arnold aiul Drew 1987, Brigham 1982. Cantcrbm \ and NelT 1980). After hatching, the Liixac tall into the water where they li\c undci stones, vegetation, and other objects. Sialid lar\ac are aquatic predators ol" small aquatic m-sccls (Pi'ilchaid aiul l.cischnci' h)7.^). liilly dcNclopcti lar\ae crawl mil ot the water onto land, and each forms an earthen cell
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