Observations on the larva and pupa of the caddisfly genus Hagenella (Trichoptera: Phryganeidae)

Abstract

The literature on Trichoptera indicates that there have been few if any records for the immature stages of species of Hagenella since the original descriptions for the European species H. clathrata by SILFVENIUS, STRÜCK, and ULMER in the first decade of this century. New data presented here on larval and pupal morphology of this species are therefore of interest, and particularly so because they show some discrepancy from the diagnostic characters traditionally cited for it. Examination of larval exuviae from pupal cases of specimens of H. clathrata reared in Finland by SILFVENIUS in 1904 has revealed close concordance with larvae recently reared in England; and larvae with these same general characters recently collected in Canada are probably those of the North American species H. canadensis. Discrepancy between available specimens and traditional larval diagnoses may reflect variation in the small local populations in which H. clathrata occurs, or colour changes in preserved material may also have some bearing. Additional diagnostic characters are proposed.