T.E.R:R.A.I.N - Taranaki Educational Resource: Research, Analysis and Information Network


Mayfly nymph (Genus: Oniscigaster) Swimming Mayfly nymph

Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Ephemeroptera
Suborder: Schistonota
Superfamily: Baetoidea
Family: Oniscigastridae 
Genus: Oniscigaster
Species: O. distans
Binominal name: Oniscigaster distans
Common name: Swimming Mayfly nymph

Oniscigaster mayfly nymphs have a torpedo-like body form, fringed caudal filaments (“tails”), large spines along the sides and top of the abdomen, and rounded gills lying on the top of the abdomen.
Oniscigaster larvae usually inhabit in pools in stony or gravely, bush covered streams.
They are thought to be detritivores, feeding on streambed algae and decomposing plant matter.
The presence of Oniscigaster suggests good habitat and water quality conditions, especially if other mayfly or stonefly groups are also present.

Photo of Oniscigaster distans a swimming mayfly nymph