Stonefly (Megaleptoperla)

Taxonomic group

Gripopterygidae: Megaleptoperla

Diagnostic features

Megaleptoperla stonefly nymphs are larger than most aquatic insects. They have a rosette of anal gills between the cerci (“tails”). Underneath the anal gills are “subanal lobes” that have distinct spines pointing posteriorly.

[Megaleptoperla]. Image: Stephen Moore Image — Megaleptoperla. Image: Stephen Moore

[Megaleptoperla]. Subanal lobe with spine. Image: Stephen Moore Image — Megaleptoperla. Subanal lobe with spine. Image: Stephen Moore

Typical habitats

Megaleptoperla nymphs are common in many bush covered, cold water, stony streams, and sometimes weedy streams.

Feeding

They may feed on a range of organic matter accumulating on stream beds. We have observed one feeding on a midge larva.

Indicator value

Hard bottom: 9
Soft bottom: 7.3

The tolerance values (ranging from 0 to 10) give an indication of which are the sensitive taxa (values of 8 or more) and which are the tolerant taxa (values of 3 or less). For more information see: Indicator species

Megaleptoperla nymphs are only likely to be common or abundant in streams with good habitat and water quality. They have tolerance values of 9 (hard bottom sites) and 7.3 (soft bottom sites).