Free-living caddis (Ecnomina)

Taxonomic group

Ecnomidae: Ecnomina

Diagnostic features

The ecnomid caddisfly larvae have at least some hardening (sclerotisation) on each of the 3 thoracic segments. Unlike the hydropsychids, there are no gills under the abdomen. In Ecnomina the sclerotisation of the mesothorax and metathorax is only partial and has little pigmentation, unlike in Zelandoptila where the sclerotisation is complete and more pigmented.

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

[Ecnomina]. Partial sclerotisation on the mesonotum and metanotum. Image: Stephen Moore Image — Ecnomina. Partial sclerotisation on the mesonotum and metanotum. Image: Stephen Moore

Typical habitats

They are common in some bush-covered streams, particularly north of Auckland.

Feeding

Ecnomina larvae are thought to be predators, feeding on other stream invertebrates.

Indicator value

Hard bottom: 8
Soft bottom: 9.6

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

Ecnomina larvae are most commonly found in streams with good water quality. They have relatively high tolerance values of 8 (hard bottom sites) and 9.6 (soft bottom sites).