Life History Patterns of Insects in an Intermittent and a Permanent Stream

Abstract

Samples were taken in an intermittent stream (dries only at some locations) and a permanent stream in a single watershed in Tompkins County, New York, over a 3-yr period to compare the life history patterns of specialist species (occurring primarily in intermittent streams), facultative species (occurring in both permanent and intermittent streams) and permanent-stream species (occurring primarily in permanent habitats). We also tested the hypothesis that to avoid the dry period, populations of species grow and develop faster and emerge earlier in the intermittent than in the permanent stream. Specialist species emerged by mid-June, whereas permanent-stream species had late summer emergences. Although two of the three specialist species (Amphinemura delosa and Ameletus ludens) had drought-resistant eggs, the third (Paracapnia opis) had immediately hatching eggs. Nymphs of this last species survived the dry period either in the hyporheic zone or in riffles that did not dry. Only one of two facultative spec...