Net-building caddis (Diplectrona)

Taxonomic group

Hydropsychidae: Diplectrona

Diagnostic features

Hydropsychid caddis larvae have hardened (sclerotised) plates on each of the 3 thoracic segments, and gill tufts under the abdomen. Diplectrona caddis larvae have a more “hairy” appearance than the related Aoteapsyche, and they have 7 sets of abdominal like gills (like Aoteapsyche). In Diplectrona the foreleg trochantin (segment at the base of the leg) has a spine that is not forked, unlike Aoteapsyche.

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

[Diplectrona]. Trochantin triangular, not forked. Image: Stephen Moore Image — Diplectrona. Trochantin triangular, not forked. Image: Stephen Moore

Typical habitats

Diplectrona larvae are mostly found in bush covered streams in the lower North Island and the South Island.

Feeding

They construct filter-feeding nets attached to the streambed to trap drifting particulate food items.

Indicator value

Hard bottom: 9
Soft bottom: unassigned

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

Diplectrona larvae are most likely to be found in streams with good water quality. They have a tolerance value of 9 for hard bottom sites (there is no soft bottom tolerance value).