Stony cased caddis (Pycnocentrodes)

Taxonomic group

Conoesucidae: Pycnocentrodes

Diagnostic features

Pycnocentrodes caddis larvae construct mobile cases covered in sand grains and small stones. The top of their head is much flatter than other sandy/stony cased genera like Pycnocentria or Pycnocentrella. Pycnocentrodes larvae often attach larger stones or snails to the sides of their case.

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

[Pycnocentrodes]. Flat head. Image: Stephen Moore Image — Pycnocentrodes. Flat head. Image: Stephen Moore

Typical habitats

Pycnocentrodes larvae are common in streams with stony or gravelly beds, both in bush covered and farmland areas.

Feeding

They are collector-gatherers feeding on fine organic matter and grazing on streambed algae.

Indicator value

Hard bottom: 5
Soft bottom: 3.8

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

An abundance of Pycnocentrodes larvae indicates at least moderate to good water quality, but many mayfly, stonefly and other caddisfly groups are better indicators of good water quality. They have tolerance values of 5 (hard bottom sites) and 3.8 (soft bottom sites).