Abstract
Three species of Pycnopsyche occur in West Creek, the larvae inhabiting allochthonous organic materials. The rapid growth, and early aestivation and emergence of the rarest species, P. scabripennis (Rambur), diminishes interspecific interactions between larvae. P. gentilis (McLachlan) and P. luculenta (Betten) are contemporaneous and the larvae are similar in size but differ in case materials and habitat preferences. Adult males of each species differ in the peak time of arrival at light when active on the same night. The life history and behaviour patterns are discussed in relation to the coexistence of congeneric species.
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