Free-living caddis (Psilochorema)

Taxonomic group

Hydrobiosidae: Psilochorema

Diagnostic features

The New Zealand hydrobiosid caddis larvae have pincers on their forelegs. Psilochorema larvae tend to have a long, slender body, prothorax (first segment behind the head) and head. The prosternal plate (shield-like plate between the forelegs) is much longer than wide. Typically the head and pronotum are red-brown in colour.

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

[Psilochorema]. Prosternal plate much longer than wide. Image: Stephen Moore Image — Psilochorema. Prosternal plate much longer than wide. Image: Stephen Moore

Typical habitats

Psilochorema larvae can be common in bush-covered and farmland stony streams.

Feeding

They are predators, feeding on other stream invertebrates.

Indicator value

Hard bottom: 8
Soft bottom: 7.8

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

Psilochorema larvae can be an indication of good water quality, particularly if they are found along with a range of mayfly and stonefly taxa. They have tolerance values of 8 (hard bottom sites) and 7.8 (soft bottom sites).