Free-living caddis (Polyplectropus)

Taxonomic group

Polycentropodidae: Polyplectropus

Diagnostic features

Polyplectropus caddis larvae have no mobile case, no chelae (pincers) and they have a distinctly speckled head pattern. The head pattern does not include a curved line of spots (the related Plectrocnemia has a curved line of spots across the head).

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

[Polyplectropus] filter feeding net. Image: Stephen Moore Image — Polyplectropus filter feeding net. Image: Stephen Moore

Typical habitats

Polyplectropus larvae are common in slow-flowing gravelly streams, or soft bottom streams with woody debris, throughout New Zealand.

Feeding

They construct delicate filter-feeding nets to trap drifting particulate food items, possibly including other invertebrates and plant fragments.

Indicator value

Hard bottom: 8
Soft bottom: 8.1

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

Polyplectropus larvae are most common in streams of moderate to good quality, as reflected by their tolerance values of 8 (hard bottom sites) and 8.1 (soft bottom sites).