Life History, Burrowing Behavior, and Distribution of Neohermes filicornis (Megaloptera: Corydalidae), a Long-Lived Aquatic Insect in Intermittent Streams

Abstract

Abstract. Several species of fishflies (Megaloptera: Corydalidae: Chauliodinae) have been reported from intermittent streams in western North America, but the life histories and distributions of these species are poorly understood. We studied the life history of Neohermes filicornis (Banks 1903) for 2 years in Donner Creek (Contra Costa County, California), a small intermittent stream that flows for 5–7 months per year. Neohermes filicornis had a 3–4-year life span and larval growth was asynchronous. Analysis of gut contents showed that larvae were generalist predators of aquatic insect larvae including Diptera, Ephemeroptera, and Plecoptera. Final instars dug pupal chambers in the streambed and began pupation within several days of stream drying. Dry conditions in 2007 resulted in stream drying 50 days earlier than in 2006, which was reflected in earlier pupation and adult emergence in 2007 than in 2006. Pupal and adult stages each lasted for 1–2 weeks. Although active burrowing into the dry streambed wa...