The systematics and ecology of three species of Caddis fly larvae in Lake Rotorua

Abstract

Three caddis fly species are the subject of this study. They are Triplectides cephalotes (Walker), Hudsonema amabilis (McLachlan) and Oecetis unicolor (McLachlan). The study was carried out around the Hamurana Stream mouth in Lake Rotorua. The systematics of the three species are presented in Part One. The ecology of the larvae of these species is examined, and they are found to differ in their preferences for the substrate on which they live, the food they eat, and the size and type of material with which they build their cases. It is concluded that their exploitation of the resources of the environment is consistent with the Coexistence Principle on which the study is based. Analysis of the stomach contents of trout reveals that these caddis larvae are the major item of diet in the Hamurana area. In conclusion, an account of the history of caddis fly populations in Lake Rotorua is presented, and some implications of the recent upsurge in weed growth are discussed.