Spatial distribution on river banks of Isoperla nevada (Plecoptera, Perlodidae), Chloroperla nevada (Plecoptera, Chloroperlidae) and Sericostoma cf. vittatum (Trichoptera, Sericostomatidae)

Abstract

The models of spatial distribution on river banks of adults of two species of Plecoptera and one of Trichoptera were studied. Isoperla nevada showed a contagious distribution, Chloroperla nevada an aleatory one, and Sericostoma cf. vittatum a clear tendency to be distributed in pairs. Data of the mean density of individuals per square are given for the three species. The existence of possible aggregation sites or of mate‐guarding behaviour are discussed for the different species.

Key words:

• Isoperla nevada
• Chloroperla nevada
• Sericostoma cf. vittatum
• Plecoptera
• Trichoptera
• Spatial distribution
• Aggregation
• Aggregation advantages