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Free-living caddis (Hydrobiosella)

Taxonomic group

Philopotamidae: Hydrobiosella

Diagnostic features

Hydrobiosella caddisfly larvae have a pale body with orange head and prothorax (first segment behind the head). The hind edge of the pronotum (which covers the prothorax) is marked by a thick black band.

Typical habitats

Hydrobiosella larvae are common in many stony bush-covered streams.


They are known to be both collector-gatherers (feeing on organic detritus and algae) and predators (feeding on other stream invertebrates).

Indicator value

  • Hard bottom: 9
  • Soft bottom: 7.6

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

An abundance of Hydrobiosella larvae indicates good water quality, particularly where mayfly and stonefly nymphs are also abundant. They have high tolerance values of 9 (hard bottom sites) and 7.6 (soft bottom sites).