Life History of <I>Neophylax rickeri</I> (Trichoptera: Uenoidae) in Two Northern California Streams

Abstract

We studied the life history of the caddisfly Neophylax rickeri Milne (Trichoptera: Uenoidae) in two coastal northern California (Marin Co.) streams, Redwood Creek (a third order stream) and Webb Creek (a first order stream). Features were described for egg (oviposition location, predation, and egg mass phenology), larval (instar determination, instar phenology, voltinism, and case building), pupal (prepupal diapause, pupation phenology, mortality, and predation), and adult (emergence phenology, sex ratios, protandry, size, and longevity) stages. Oviposition on the downstream-facing sides of rocks occurred primarily in November in both streams; however, egg masses were also present from April through November in Webb Creek. Egg masses in Redwood Creek, but not Webb Creek, sometimes contained an egg predator, Acanthocnema sp. (Diptera: Scathophagidae). N. rickeri has five instars. The Redwood Creek population exhibits a synchronous univoltine pattern of development, but in Webb Creek a more variable pattern is present, with the majority of the population being univoltine with a small bivoltine summer generation. The Redwood Creek population had a longer prepupal diapause, but a shorter emergence period than Webb Creek. Prepupal mortality was highest in the summer in Redwood Creek, but it was overall low in Webb Creek. Pupal and adult sex ratios indicated protandry, with males emerging before females by ≈2 wk in both streams. The differences in the life histories of N. rickeri between streams for voltinism, life cycle timing, mortality, and pupal diapause suggest that physical habitat differences likely influence the variation in life history of this species.